U.S. patent number 4,048,128 [Application Number 05/634,064] was granted by the patent office on 1977-09-13 for thermally stabilized segmented copolyester adhesive.
This patent grant is currently assigned to E. I. Du Pont de Nemours and Company. Invention is credited to Ernest Francis Eastman.
United States Patent |
4,048,128 |
Eastman |
September 13, 1977 |
Thermally stabilized segmented copolyester adhesive
Abstract
Thermally stabilized thermoplastic segmented copolyester of
recurring short chain ester units and long chain ester units joined
through ester linkages, having a melt index of less than 150 and a
melting point of at least 90.degree. C., an inherent viscosity in
the range of 1.0 to 1.7 and an acid number not greater than 3,
stabilized with 0.05 to 3.0 percent by weight, based on the weight
of copolyester, of an alkaline earth oxide. Improved stabilizing
effect can be achieved when 0.25 to 2.5 percent by weight, based on
the weight of copolyester, of the alkaline earth oxide is used in
conjunction with 0.25 to 2.5 percent by weight, based on the weight
of copolyester, of a substantially linear polycarbodiimide.
Additional optional materials that can be added with the
stabilizer, based on the weight of copolyester, include: 0.25 to
5.0 percent by weight of a compound taken from the group consisting
of hindered phenols, nitrogen-containing hindered phenols and
hindered secondary amines; 0.25 to 5.0 percent by weight of a
thioalkylpropionate ester of 12 to 18 carbon atoms; 0.25 to 5.0
percent by weight of a phosphorous acid ester; or mixtures thereof.
A useful stabilized adhesive composition comprises (A) 1 to 99
percent by weight of segmented copolyester, (B) 1 to 99 percent by
weight of a compatible low molecular weight thermoplastic resin,
and (C) 0.1 to 4.0 percent by weight, based on the weight of
copolyester and resin of the alkaline earth oxide, preferably
calcium oxide, stabilizer.
Inventors: |
Eastman; Ernest Francis
(Wilmington, DE) |
Assignee: |
E. I. Du Pont de Nemours and
Company (Wilmington, DE)
|
Family
ID: |
27033730 |
Appl.
No.: |
05/634,064 |
Filed: |
November 21, 1975 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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443984 |
Feb 20, 1974 |
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Current U.S.
Class: |
524/147; 156/332;
524/111; 524/153; 524/258; 524/343; 524/351; 524/604; 525/123;
525/418; 524/100; 524/151; 524/255; 524/333; 524/347; 524/433;
524/539; 524/605; 525/177; 525/451 |
Current CPC
Class: |
C08G
63/672 (20130101); C08K 3/22 (20130101); C08L
67/025 (20130101); C09J 167/02 (20130101); C08K
3/22 (20130101); C08L 67/02 (20130101); C08L
67/025 (20130101); C09J 167/02 (20130101); C08L
2666/02 (20130101); C08L 2666/02 (20130101); C08L
2666/54 (20130101); C08L 2666/02 (20130101); C08L
2666/54 (20130101) |
Current International
Class: |
C08L
67/02 (20060101); C08G 63/00 (20060101); C08G
63/672 (20060101); C08K 3/00 (20060101); C08K
3/22 (20060101); C09J 167/00 (20060101); C09J
167/02 (20060101); C08L 67/00 (20060101); C08K
003/22 (); C08L 067/00 (); C08L 091/00 () |
Field of
Search: |
;260/860,75T,4R,45.7R,23,26,28,22R,843,873,28.5AS,829 ;156/332 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Warner, 28th Annual Technical Conference, 1973 Reinforced
Plastics/Composites Institute The Society of the Plastics Industry,
Inc., Sec. 19-E, pp. 1-12..
|
Primary Examiner: Schain; Howard E.
Assistant Examiner: Danison, Jr.; W. C.
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATION
This application is a continuation-in-part of application Ser. No.
443,984, filed Feb. 20, 1974, now abandoned.
Claims
I claim:
1. A thermally stabilized thermoplastic segmented copolyester
consisting essentially of a multiplicity of recurring short chain
ester units and long chain ester units joined through ester
linkages, said short chain ester units amounting to 15 to 75
percent by weight of said copolyester and being of the formula
##STR10## and said long chain ester units amounting to 25 to 85
percent by weight of said copolyester and being of the formula
##STR11## wherein R is the divalent radical remaining after removal
of the carboxyl groups from a dicarboxylic acid having a molecular
weight of less than 350, D is the divalent radical remaining after
removal of the hydroxyl groups from organic diol having a molecular
weight of less than 250, and G is the divalent radical remaining
after removal of the terminal hydroxyl groups from long chain
glycol having an average molecular weight of 350 to 6000, said
copolyester having a melt index of less than 150, a melting point
of at least 90.degree. C., an inherent viscosity in the range of
1.0 to 1.7 and an acid number not greater than 3, stabilized with
0.05 to 3.0 percent by weight, based on the weight of copolyester,
of an alkaline earth oxide stabilizer.
2. The copolyester of claim 1 in which the alkaline earth oxide is
calcium oxide.
3. The copolyester of claim 1 in which R is a divalent saturated
cyclic, aromatic or saturated aliphatic, radical remaining after
removal of the carboxyl groups from a saturated cyclic, aromatic or
saturated aliphatic, dicarboxylic acid.
4. The copolyester of claim 3 in which R is a divalent aromatic
radical remaining after removal of the carboxyl groups from an
aromatic dicarboxylic acid.
5. The copolyester of claim 1 in which there is present in
combination with the alkaline earth oxide 0.25 to 2.5 percent by
weight, based on the weight of copolyester, of a substantially
linear polycarbodiimide having an average of at least two
carbodiimide groups per molecule.
6. The copolyester of claim 1 in which there is present in
combination with the alkaline earth oxide 0.25 to 5.0 percent by
weight, based on the weight of copolyester, of at least one
compound taken from the group consisting of hindered phenols,
nitrogen-containing hindered phenols and hindered secondary
amines.
7. The copolyester of claim 5 in which there is present in
combination with the alkaline earth oxide and polycarbodiimide 0.25
to 5.0 percent by weight, based on the weight of copolyester, of at
least one compound taken from the group consisting of hindered
phenols, nitrogen-containing hindered phenols and hindered
secondary amines.
8. The copolyester of claim 1 in which there is present 0.25 to 5.0
percent by weight, based on the weight of copolyester, of a
dialkylthiodipropionate ester wherein alkyl is of 12 to 18 carbon
atoms.
9. The copolyester of claim 1 in which there is present 0.25 to 5.0
percent by weight, based on the weight of copolyester, of a
phosphorous acid ester of the formula ##STR12## where R.sub.1,
R.sub.2 and R.sub.3 are C.sub.1 to C.sub.18 aliphatic, C.sub.6 to
C.sub.15 aromatic and combinations thereof.
10. The copolyester of claim 1 in which the short chain ester units
amount to 15 to 65 percent by weight of the copolyester, the long
chain ester units amount to 35 to 85 percent by weight of the
copolyester, and the long chain glycol has a melting point of less
than 75.degree. C.
11. The copolymer of claim 1 in which the short chain ester units
amount to 15 to 50 percent by weight of copolyester, the long chain
ester units amount to 50 to 85 percent by weight of copolyester,
the dicarboxylic acid being 55 to 95 percent by weight terephthalic
acid, D is the divalent radical remaining after removal of the
hydroxyl groups from butanediol, and G is the divalent radical
remaining after removal of the terminal groups from
polytetramethylene ether glycol having an average molecular weight
of 600 to 3500, the copolyester having a melt index of less than
30, a melting point of 90.degree. to 130.degree. C., an inherent
viscosity in the range of 1.4 to 1.6, and an acid number less than
2.
12. The copolyester of claim 11 in which the dicarboxylic acid is a
mixture of terephthalic acid and isophthalic acid.
13. The copolyester of claim 12 in which the polytetramethylene
ether glycol has a molecular weight of 600 to 2100.
14. The copolyester of claim 13 in which the short chain ester
units amount to 15 to less than 30 percent by weight of the
copolyester and the long chain ester units amount to more than 70
to 85 percent by weight of the copolyester.
15. The copolyester of claim 14 in which the mixture of
terephthalic acid and isophthalic acid contains 70 to 95 percent by
weight of terephthalic acid.
16. The copolyester of claim 5 in which the polycarbodiimide is
represented by the formula:
where R.sub.1, R.sub.2 and R.sub.3 are C.sub.1 --C.sub.12
aliphatic, C.sub.5 --C.sub.15 cycloaliphatic, or C.sub.6 --C.sub.15
aromatic divalent hydrocarbon radicals, and combinations thereof;
X.sub.1 and X.sub.2 are hydrogen, ##STR13## where R.sub.4, R.sub.5
and R.sub.6 are C.sub.1 --C.sub.12 aliphatic, C.sub.5 --C.sub.15
cycloaliphatic, and C.sub.6 --C.sub.15 aromatic monovalent
hydrocarbon radicals and combinations thereof, and additionally
R.sub.4 or R.sub.5 can be hydrogen; and n is a number of at least
one.
17. The copolyester of claim 6 in which the compound is a hindered
phenol.
18. The copolyester of claim 17 in which the hindered phenol is
tetrakis[methylene-3-(3',5'-ditertiarybutyl-4'-hydroxyphenol)
propionate] methane.
19. The copolyester of claim 6 in which the compound is a
nitrogen-containing hindered phenol.
20. The copolyester of claim 6 in which the compound is a secondary
aromatic amine.
21. The copolyester of claim 9 in which the phosphorous acid ester
is trinonylphenylphosphite.
22. A thermally stabilized thermoplastic hot melt adhesive
composition in the molten state which comprises, based on the total
thermoplastic components, (A) 1 to 99 percent by weight of
thermoplastic segmented copolyester consisting essentially of a
multiplicity of recurring short chain ester units and long chain
ester units joined through ester linkages, said short chain ester
units amounting to 15 to 75 percent by weight of said copolyester
and being of the formula ##STR14## and said long chain ester units
amounting to 25 to 85 percent by weight of said copolyester and
being of the formula ##STR15## wherein R is the divalent radical
remaining after removal of the carboxyl groups from a dicarboxylic
acid having a molecular weight of less than 350, D is the divalent
radical remaining after removal of the hydroxyl groups from organic
diol having a molecular weight of less than 250, and G is the
divalent radical remaining after removal of the terminal hydroxyl
groups from long chain glycol having an average molecular weight of
350 to 6000, said copolyester having a melt index of less than 150,
a melting point of at least 90.degree. C., an inherent viscosity in
the range of 1.0 to 1.7, and an acid number of less than 3; (B) 1
to 99 percent by weight of low molecular weight thermoplastic resin
which forms compatible mixtures with the segmented copolyester, is
thermally stable at 150.degree. C., and has a melt viscosity of
less than 10,000 centipoises at 200.degree. C.; stabilized against
substantial loss in viscosity in said molten state with (C) 0.1 to
4.0 percent by weight, based on the weight of copolyester and
resin, of an alkaline earth oxide.
23. The composition of claim 22 in which the alkaline earth oxide
is calcium oxide.
24. The composition of claim 22 in which R is a divalent saturated
cyclic, aromatic or saturated aliphatic, radical remaining after
removal of the carboxyl groups from a saturated cyclic, aromatic or
saturated aliphatic, dicarboxylic acid.
25. The composition of claim 24 in which R is a divalent aromatic
radical remaining after removal of the carboxyl groups from an
aromatic dicarboxylic acid.
26. The composition of claim 22 in which there is present in
combination with the alkaline earth oxide 0.1 to 1.0 percent by
weight, based on the weight of copolyester and resin, of a
substantially linear polycarbodiimide having an average of at least
two carbodiimide groups per molecule represented by the
formula:
where R.sub.1, R.sub.2 and R.sub.3 are C.sub.1 --C.sub.12
aliphatic, C.sub.5 --C.sub.15 cycloaliphatic, or C.sub.6 --C.sub.15
aromatic divalent hydrocarbon radicals, and combinations thereof;
X.sub.1 and X.sub.2 are hydrogen, ##STR16## where R.sub.4, R.sub.5
and R.sub.6 are C.sub.1 --C.sub.12 aliphatic, c.sub.5 --C.sub.15
cycloaliphatic, and C.sub.6 --C.sub.15 aromatic monovalent
hydrocarbon radicals and combinations thereof, and additionally
R.sub.4 or R.sub.5 can be hydrogen; and n is number of at least
one.
27. The compositin of claim 22 in which there is present in
combination with the alkaline earth oxide 0.1 to 2.0 percent by
weight, based on the weight of copolyester and resin, of at least
one compound taken from the group consisting of hindered phenols,
nitrogen-containing hindered phenols and hindered secondary
amines.
28. The composition of claim 26 in which there is present in
combination with the alkaline earth oxide and polycarbodiimide 0.1
to 2.0 percent by weight, based on the weight of copolyester and
resin, of at least one compound taken from the group consisting of
hindered phenols, nitrogen-containing hindered phenols and hindered
secondary amines.
29. The composition of claim 22 in which there is present 0.1 to
2.0 percent by weight, based on the weight of copolyester and
resin, of a dialkylthiodipropionate ester wherein alkyl is of 12 to
18 carbon atoms.
30. The composition of claim 22 in which there is present 0.1 to
2.0 percent by weight, based on the weight of copolyester and
resin, of a phosphorous acid ester of the formula ##STR17## where
R.sub.1, R.sub.2 and R.sub.3 are C.sub.1 to C.sub.18 aliphatic,
C.sub.6 to C.sub.15 aromatic, and combinations thereof.
31. The composition of claim 22 in which the low molecular weight
thermoplastic resin is selected from the group consisting of
hydrocarbon resins, bituminous asphalts, coal tar pitches, rosins,
rosin based alkyd resins, phenolic resins, chorinated aliphatic
hydrocarbon waxes, chlorinated polynuclear aromatic hydrocarbons,
and mixtures thereof.
32. The composition of claim 31 in which the thermoplastic
composition comprises 5 to 95 percent by weight of segmented
copolyester and 5 to 95 percent by weight of low molecular weight
thermoplastic resin.
33. The composition of claim 31 which comprises 20 to 60 percent by
weight of segmented copolyester and 40 to 80 percent by weight of
low molecular weight thermoplastic resin.
34. The composition of claim 31 in which the dicarboxylic acid is
an aromatic dicarboxylic acid of 8 to 16 carbon atoms, the low
molecular weight diol is aliphatic diol of 2 to 8 carbon atoms, and
the long chain glycol is poly(alkylene ether) glycol in which the
alkylene group is of 2 to 9 carbon atoms.
35. the composition of claim 34 in which the short chain ester
units amount to about 30 to 65 percent by weight of the
copolyester, the long chain ester units amount to about 35 to 70
percent by weight of the copolyester, and the copolyester has a
melt index of less than 50, a melting point of at least 140.degree.
C., an inherent viscosity of about 1.4 to 1.6 and an acid number of
1 to less than 2.
36. The composition of claim 35 in which the dicarboxylic acid is
an aromatic dicarboxylic acid selected from the group consisting of
terephthalic acid, and mixtures of terephthalic and isophthalic
acids, the low molecular weight diol is butanediol, and the long
chain glycol is polytetramethylene ether glycol having a molecular
weight of 600 to 3000.
37. The composition of claim 36 which comprises 15 to 45 percent by
weight of segmented copolyester and 55 to 85 percent by weight of
low molecular weight thermoplastic resin.
38. The composition of claim 37 in which the low molecular weight
thermoplastic resin is a mixture of at least two low molecular
weight thermoplastic resins.
39. The composition of claim 38 in which one of the low molecular
weight thermoplastic resins is a styrene polymer.
40. The composition of claim 38 in which one of the low molecular
weight thermoplastic resins is a coumarone-indene resin.
41. The composition of claim 38 in which one of the low molecular
weight thermoplastic resins is a bituminous asphalt.
42. The composition of claim 38 in which one of the low molecular
weight thermoplastic resins is a rosin.
43. The composition of claim 38 in which one of the low molecular
weight thermoplastic resins is a terpene resin.
44. The composition of claim 31 in which the dicarboxylic acid is a
mixture of terephthalic acid and isophthalic acid.
45. The composition of claim 44 in which the polytetramethylene
ether glycol has a molecular weight of 600 to 2100.
46. The composition of claim 45 in which the short chain ester
units amount to 15 to less than 30 percent by weight of the
copolyester and the long chain ester units amount to more than 70
to 85 percent of the copolyester.
47. The composition of claim 46 in which the mixture of
terephthalic acid and isophthalic acid contains 60 to 95 percent by
weight of terephthalic acid.
48. Method of preparing a thermoplastic composition which comprises
blending in molten form, based on the total thermoplastic
components,
A. 1 to 99 percent by weight of thermoplastic segmented copolyester
consisting essentially of a multiplicity of recurring short chain
ester units and long chain ester units joined through ester
linkages, said short chain ester units amounting to 15 to 75
percent by weight of said copolyester and being of the formula:
##STR18## and said long chain ester units amounting to 25 to 85
percent by weight of said copolyester and being of the formula:
##STR19## wherein R is the divalent radical remaining after removal
of the carboxyl groups from dicarboxylic acid having a molecular
weight of less than 350, D is the divalent radical remaining after
removal of the hydroxyl groups from organic diol having a molecular
weight of less than 250, and G is the divalent radical remaining
after removal of the terminal hydroxyl groups from long chain
glycol having an average molecular weight of 350 to 6000, said
copolyester having a melt index of less than 150, a melting point
of at least 90.degree. C., an inherent viscosity in the range of
1.0 to 1.7, and an acid number not greater than 3.0;
B. 1 to 99 percent by weight of low molecular weight thermoplastic
resin which forms compatible mixtures with the segmented
copolyester, is thermally stable at 150.degree. C., and has a melt
viscosity of less than 10,000 centipoises at 200.degree. C.;
stabilized against substantial loss of viscosity in said molten
form with
C. 0.1 to 4.0 percent by weight, based on the weight of copolyester
and resin, of an alkaline earth oxide.
49. The method of claim 48 in which the alkaline earth oxide is
calcium oxide.
50. The method of claim 48 in which R is a divalent saturated
cyclic, aromatic or saturated aliphatic radical remaining after
removal of the carboxyl groups from a saturated cyclic, aromatic or
saturated aliphatic, dicarboxylic acid.
51. The method of claim 50 in which R is a divalent aromatic
radical remaining after removal of the carboxyl groups from an
aromatic dicarboxylic acid.
52. The method of claim 48 in which there is present in combination
with the alkaline earth oxide 0.1 to 1.0 percent by weight, based
on the weight of copolyester and resin, of a substantially linear
polycarbodiimide having an average of at least two carbodiimide
groups per molecule represented by the formula:
where R.sub.1, R.sub.2 and R.sub.3 are C.sub.1 -C.sub.12 aliphatic,
C.sub.5 -C.sub.15 cycloaliphatic, or C.sub.6 -C.sub.15 aromatic
divalent hydrocarbon radicals, and combinations thereof; X.sub.1
and X.sub.2 are hydrogen, ##STR20## where R.sub.4, R.sub.5 and
R.sub.6 are C.sub.1 -C.sub.12 aliphatic, C.sub.5 -C.sub.15
cycloaliphatic, and C.sub.6 -C.sub.15 aromatic monovalent
hydrocarbon radicals and combinations thereof, and additionally
R.sub.4 or R.sub.5 can be hydrogen; and n is a number of at least
one.
53. The method of claim 48 in which there is present with the
alkaline earth oxide 0.1 to 2.0 percent by weight, based on the
weight of copolyester and resin, of at least one compound taken
from the group consisting of hindered phenols, nitrogen-containing
hindered phenols and hindered secondary amines.
54. The method of claim 52 in which there is present in combination
with the alkaline earth oxide and polycarbodiimide 0.1 to 2.0
percent by weight, based on the weight of copolyester and resin, of
at least one compound taken from the group consisting of hindered
phenols, nitrogen-containing phenols and hindered secondary
amines.
55. The method of claim 48 in which there is present 0.1 to 2.0
percent by weight, based on the weight of copolyester and resin, of
a dialkylthiodipropionate ester wherein alkyl is of 12 to 18 carbon
atoms.
56. The method of claim 48 in which there is present 0.1 to 2.0
percent by weight, based on the weight of copolyester and resin, of
a phosphorous acid ester of the formula ##STR21## where R.sub.1,
R.sub.2 and R.sub.3 are C.sub.1 to C.sub.18 aliphatic C.sub.6 to
C.sub.15 aromatic, and combinations thereof.
57. The method of claim 48 in which the short chain ester units
amount to 15 to 65 percent by weight of the copolyester, the long
chain ester units amount to 35 to 85 percent by weight of the
copolyester, and the long chain glycol has a melting point of less
than 75.degree. C.
58. The method of claim 57 in which the low molecular weight
thermoplastic resin is selected from the group consisting of
hydrocarbon resin, bituminous asphalts, coal tar pitches, rosins,
phenolic resins, chlorinated aliphatic hydrocarbon waxes,
chlorinated polynuclear aromatic hydrocarbons and mixtures
thereof.
59. The method of claim 58 in which the stabilized segmented
copolyester is first melted and the low molecular weight
thermoplastic resin is added to the melt.
60. The method of claim 58 in which the low molecular weight
thermoplastic resin is first melted and the stabilized segmented
copolyester is added to the melt.
61. The method of claim 58 in which the segmented copolyester and
the low molecular weight thermoplastic resin are blended together
in finely divided form and melted together and the stabilizer is
present prior to blending.
62. The method of claim 58 in which the segmented copolyester and
the low molecular weight thermoplastic resin are blended together
in finely divided form and melted together, the alkaline earth
oxide being added with the other components.
63. The method of claim 62 in which there is added with the
alkaline earth oxide a substantially linear polycarbodiimide having
an average of at least two carbodiimide groups per molecule
represented by the formula:
where R.sub.1, R.sub.2 and R.sub.3 are C.sub.1 -C.sub.12 aliphatic,
C.sub.5 -C.sub.15 cycloaliphatic, or C.sub.6 -C.sub.15 aromatic
divalent hydrocarbon radicals, and combinations thereof; X.sub.1
and X.sub.2 are hydrogen, ##STR22## where R.sub.4, R.sub.5 and
R.sub.6 are C.sub.1 -C.sub.12 aliphatic, C.sub.5 -C.sub.15
cycloaliphatic, and C.sub.6 -C.sub.15 aromatic monovalent
hydrocarbon radicals and combinations thereof, and additionally
R.sub.4 or R.sub.5 can be hydrogen; and n is a number of at least
one.
64. The method of claim 63 in which there is present with the
alkaline earth oxide and substantially linear polycarbodiimide at
least one compound taken from the group consisting of hindered
phenols, nitrogen-containing hindered phenols and hindered
secondary amines.
65. The method of claim 64 in which there is also present a
dialkylthiodipropionate ester wherein alkyl is of 12 to 18 carbon
atoms.
66. The method of claim 65 in which there is also present
phosphorous acid esters of the formula ##STR23## where R.sub.1,
R.sub.2 and R.sub.3 are C.sub.1 to C.sub.18 aliphatic, C.sub.6 to
C.sub.15 aromatic, and combinations thereof.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to stabilized thermoplastic, segmented
copolyesters, to blends of such stabilized copolyesters with one or
more compatible low molecular weight thermoplastic resins and to a
method for preparing such blends.
2. Description of the Prior Art
Copolyesters, and particularly segmented copolyesters, are used in
the formulation of adhesives such as those useful as hot melt
adhesives. Such adhesive compositions are described in U.S. Pat.
No. 3,832,314 and Hoh and Reardon Ser. No. 439,848, filed Feb. 6,
1974. The compositions of U.S. Pat. No. 3,832,314 have good bond
strength as hot melt adhesives and the compositions of the Hoh and
Reardon application are particularly useful as pressure sensitive
adhesives. In order to provide good adhesive properties the
viscosity of the adhesive compositions must be maintained at a
relatively constant level. It has been found that at elevated
temperatures, particularly in the range of 170.degree. to
200.degree. C., over a period of several hours the aforementioned
adhesive compositions lose viscosity and hence their bonding
properties are reduced. Known stabilizers or antioxidants such as
tetrakis[methylene-3-(3',5'-ditertiary-butyl-4'-hydroxyphenyl)
propionate] methane, and phosphite ester compounds, have been
incorporated in hot melt adhesive compositions containing segmented
copolyesters, but these stabilizers have not proved to be very
effective over extended periods of time, e.g., two hours and
more.
Materially improved stabilization of adhesive compositions
containing segmented copolyesters has been achieved as described in
U.S. Pat. No. 3,909,333 utilizing a stabilizer mixture comprising
(a) a substantially linear polycarbodiimide having an average of at
least two carbodiimide groups per molecule, and at least one
compound taken from the group consisting of (b) a hindered phenol,
nitrogen-containing hindered phenol, or secondary aromatic amine;
(c) phosphorous acid esters of the formula ##STR1## where R.sub.1,
R.sub.2 and R.sub.3 are C.sub.1 to C.sub.18 aliphatic, C.sub.6 to
C.sub.15 aromatic, and combinations thereof; and (d) a homopolymer
of an amino acrylate compound of the formula ##STR2## where R is
hydrogen or methyl, R.sup.1 is hydrogen or alkyl of 1 to 4 carbon
atoms, R.sup.2 is alkyl of 1 to 4 carbon atoms, and n is an integer
of 1 to 4 inclusive; and a random copolymer of ethylene and 20 to
40 percent by weight of the amino acrylate, each of the compounds
(b), (c) and (d) being compatible with each other and with (a).
While providing good stabilization of segmented copolyester
compositions, the stabilizer mixture of U.S. Pat. No. 3,909,333 is
relatively expensive and may create compatibility problems in some
adhesive formulations. It was therefore desirable to discover a
single stabilizer compound which is compatible in conjunction with
other components and not only provide excellent stabilization but
is inexpensive and is also compatible with known segmented
copolyester adhesive compositions.
SUMMARY OF THE INVENTION
In accordance with this invention superior stabilized thermoplastic
segmented copolyesters are provided which consist essentially of a
multiplicity of recurring short chain ester units and long chain
ester units joined through ester linkages, said short chain ester
units amounting to 15 to 75 percent by weight of said copolyester
and being of the formula ##STR3## and said long chain ester units
amounting to 25 to 85 percent by weight of said copolyester and
being of the formula ##STR4## wherein R is the divalent radical
remaining after removal of the carboxyl groups from a dicarboxylic
acid having a molecular weight of less than 350, D is the divalent
radical remaining after removal of the hydroxyl groups from organic
diol having a molecular weight of less than 250, and G is the
divalent radical remaining after removal of the terminal hydroxyl
groups from long chain glycol having an average molecular weight of
350 to 6000, said copolyester having a melt index of less than 150,
a melting point of at least 90.degree. C., an inherent viscosity in
the range of 1.0 to 1.7 and an acid number not greater than 3
stabilized with 0.05 to 3.0 percent by weight, based on the weight
of copolyester, of an alkaline earth oxide.
Improved stability, in many instances, is achieved by having
present with the alkaline earth oxide 0.25 to 2.5 percent by
weight, based on the weight of copolyester, of a substantially
linear polycarbodiimide having an average of at least two
carbodiimide groups per molecule. Optionally materials that can be
added, singly or in combination, with the alkaline earth oxide
stabilizer, optionally containing the polycarbodiimide compound,
based on the weight of copolyester, include: 0.25 to 5.0 percent by
weight of a compound taken from the group consisting of hindered
phenols, nitrogen-containing hindered phenols, and hindered
secondary amines; 0.25 to 5.0 percent by weight of a
thioalkylpropionate ester of 12 to 18 carbon atoms; 0.25 to 5.0
percent by weight of a phosphorous acid ester of the formula
##STR5## where R.sub.1, R.sub.2 and R.sub.3 are C.sub.1 to C.sub.18
aliphatic, C.sub.6 to C.sub.15 aromatic, and combinations
thereof.
The components that make up the stabilizer are compatible with one
another.
Improved stabilized thermoplastic compositions are provided which
comprise, based on the total thermoplastic components, (A) 1 to 99
percent by weight of thermoplastic segmented copolyester described
above; (B) 1 to 99 percent by weight of low molecular weight
thermoplastic resin which forms compatible mixtures with the
segmented copolyester, is thermally stable at 150.degree. C., and
has a melt viscosity of less than 10,000 centipoises at 200.degree.
C. stabilized with 0.1 to 4.0 percent by weight, based on the
weight of copolyester and resin, of an alkaline earth oxide. To
provide improved thermoplastic compositions there can be present
with the alkaline earth oxide 0.1 to 1.0 percent by weight, based
on the weight of copolyester and resin, of a substantially linear
polycarbodiimide having an average of at least two carbodiimide
groups per molecule.
Optionally, singly or in combination, the following materials can
be present with the aforementioned stabilizer or stabilizer
mixture, based on the weight of copolyester and resin: 0.1 to 2.0
parts by weight of a compound taken from the group consisting of
hindered phenols, nitrogen-containing hindered phenols and hindered
secondary amines; 0.1 to 2.0 percent by weight of a
dialkylthiodipropionate ester of 12 to 18 carbon atoms; 0.1 to 2.0
percent by weight of a phosphorous acid ester as described above.
The components that make up the stabilizer are compatible with one
another.
DETAILED DESCRIPTION OF THE INVENTION
The stabilized thermoplastic segmented copolyesters used in the
compositions of this invention consist essentially of 15 to 75
percent recurring short chain ester units and 25 to 85 percent long
chain ester units joined through ester linkages.
The term "short chain ester units", as applied to units in a
polymer chain, refers to the reaction products of low molecular
weight diols with dicarboxylic acids to form repeat units having
molecular weights of less than about 550. These units are also
referred to herein as "hard segments".
The term "long chain ester units", as applied to units in a polymer
chain, refers to the reaction products of long chain glycols with
dicarboxylic acids. These units are also referred to herein as
"soft segments". Preferably the copolyester consists essentially of
15 to 65 percent hard segments and 35 to 85 percent soft
segments.
The soft thermoplastic segmented copolyesters consist essentially
of about 15 to 50 percent recurring short chain ester units and
about 50 to 85 percent long chain ester units joined through ester
linkages. In these copolyesters the term short chain ester units,
as applied to units in a polymer chain, refers to the reaction of
butanediol (BDO) with aromatic dicarboxylic acids. In these
copolyesters the term long chain ester units, as applied to units
in a polymer chain, refers to the reaction products of
polytetramethylene ether glycol (PTMEG) with dicarboxylic acids.
Preferably, the copolyester consists essentially of about 15 to
less than 30 percent hard segments and more than 70 to 85 percent
soft segments.
The weight percent of long chain ester (LCE) units specified herein
are calculated in accordance with the following equation in which
both the numerator and denominator are expressed in grams.
______________________________________ ##STR6## A = (Moles of
PTMEG).times.(Mole Wt. of PTMEG) B = (Total Moles of phthalate as
Acid).times.(Mole Wt. of phthalic Acid Mixture) C = (Moles H.sub.2
O).times.(Mole Wt. of H.sub.2 O)
______________________________________
in this equation the moles of phthalate will be the same as the
moles of PTMEG and the moles of water will be twice that of PTMEG.
The mole weight of the phthalic acid mixture should be a weighted
average reflecting the composition of the mixture. The theoretical
polymer yield will be the grams of ingredients put into the
reaction minus the grams of by-product and excess ingredients
distilled off.
The weight percent of short chain ester (SCE) units is defined in
an analogous manner:
______________________________________ ##STR7## D = (Moles of
BDO).times.(Mole Wt. of BDO) E = (Total Moles of phthalate as
Acid).times.(Mole Wt. of phthalic Acid Mixture) F = (Moles H.sub.2
O).times.(Mole Wt. of H.sub.2 O)
______________________________________
here the moles of butanediol do not include any stoichiometric
excess.
The copolyesters used in accordance with this invention are
prepared by polymerizing with each other (a) one or more
dicarboxylic acids such as saturated cyclic, aromatic and saturated
aliphatic dicarboxlic acids, preferably aromatic dicarboxylic
acids, and (b) one or more low molecular weight diols. The term
"dicarboxylic acid", as used herein, is intended to include the
equivalents of dicarboxylic acids, that is, their esters or
ester-forming derivatives such as acid chlorides and anhydrides, or
other derivatives which behave substantially like dicarboxylic
acids in a polymerization reaction with glycol. By the term
"aromatic dicarboxylic acid" is meant a dicarboxylic acid in which
each carboxyl group is attached to a carbon atom in an isolated or
fused benzene ring, e.g., naphthalene, or a ring which is itself
fused to a benzene ring. Specifically, in preparing the soft
thermoplastic segmented copolyesters a mixture of aromatic
dicarboxylic acids containing about 55 to 95 percent by weight of
terephthalic acid, polytetramethylene ether glycol, and butanediol
are polymerized with each other.
The dicarboxylic acid monomers useful herein have a molecular
weight of less than about 350. This molecular weight requirement
pertains to the acid itself and not to its ester or ester-forming
derivative. Thus, the ester of a dicarboxylic acid having a
molecular weight greater than 350 is included in this invention
provided the acid itself has a molecular weight below about
350.
The dicarboxylic acids used in the preparation of the segmented
copolyester are aromatic, saturated cycloaliphatic, saturated
aliphatic dicarboxylic acids of low molecular weight, or mixtures
of said acids and can contain any substituent groups or combination
thereof which do not interfere with the polymerization reaction.
Representative aromatic dicarboxylic acids include terephthalic
acid, isophthalic acid, phthalic acid, bibenzoic acid, substituted
dicarboxy compounds with benzene nuclei such as
bis(p-carboxyphenyl) methane, p-oxy(p-carboxyphenyl) benzoic acid,
ethylene-bis(p-oxybenzoic acid), ethylene-bis-(p-benzoic acid),
tetramethylene-bis(p-oxybenzoic acid), 1,5-naphthalene dicarboxylic
acid, 2,6-naphthalene dicarboxylic acid, 2,7-naphthalene
dicarboxylic acid, phenanthrene dicarboxylic acid, anthracene
dicarboxylic acid, 4,4'-sulfonyl dibenzoic acid, indene
dicarboxylic acid, and the like, as well as ring substituted
derivatives thereof such as C.sub.1 -C.sub.10 alkyl, halo, alkoxy
or aryl derivatives. Hydroxy acids such as p(.beta.-hydroxyethoxy)
benzoic acid can also be used providing an aromatic dicarboxylic
acid is also present.
Representative saturated cycloaliphatic and aliphatic acids include
sebacic acid, 1,3-cyclohexane dicarboxylic acid, 1,4-cycohexane
dicarboxylic acid, adipic acid, glutaric acid, succinic acid,
oxalic acid, azelaic acid, diethyl-malonic acid, 2-ethylsuberic
acid, 2,2,3,3-tetramethylsuccinic acid, cyclopentanedicarboxylic
acid, decahydro-1,5-naphthylene dicarboxylic acid,
4,4'-bicyclohexyl dicarboxylic acid, decahydro-2,6-naphthylene
dicarboxylic acid, 4,4'-methylenebis-(cyclohexyl) carboxylic acid,
3,4-furan dicarboxylic acid, and 1,1-cyclobutane dicarboxylic acid.
Preferred saturated cycloaliphatic and aliphatic acids,
respectively, are cyclohexane-dicarboxylic acids and adipic
acid.
The preferred dicarboxylic acids for preparation of the segmented
copolyester are the aromatic acids of 8 to 16 carbon atoms,
particularly phenylene dicarboxylic acids such as phthalic,
terephthalic and isophthalic acids. The most preferred acids are
terephthalic acid and mixtures of terephthalic and isophthalic
acids. In the soft copolyester, preferably, the mixture of aromatic
dicarboxylic acids contains about 60 to 95 percent terephthalic
acid, the remainder being isophthalic acid.
The low molecular weight diols used in the preparation of the hard
segments of the copolyesters have molecular weights of less than
about 250. The term "low molecular weight diol", as used herein,
should be construed to include equivalent ester-forming
derivatives. In this case, however, the molecular weight
requirement pertains to the diol only and not to its
derivatives.
Suitable low molecular weight diols which react to form the short
chain ester units of the copolyesters include acyclic, alicyclic
and aromatic dihydroxy compounds. The preferred diols are those
with 2 to 15 carbon atoms such as ethylene, propylene,
tetramethylene, isobutylene, pentamethylene,
2,2-dimethyltrimethylene, hexamethylene and decamethylene glycols,
dihydroxy cyclohexane, cyclohexane dimethanol, resorcinol,
hydroquinone, 1,5-dihydroxy naphthalene, and the like. Especially
preferred are the aliphatic diols of 2 to 8 carbon atoms. Suitable
bis-phenols include bis(p-hydroxy) diphenyl, bis(p-hydroxyphenyl)
methane, bis(p-hydroxyphenyl) ethane, bis(p-hydroxyphenyl) propane
and 2,2-bis(p-hydroxyphenyl) propane. Equivalent ester-forming
derivatives of diols are also useful. For example, ethylene oxide
or ethylene carbonate can be used in place of ethylene glycol.
The long chain glycols used to prepare the soft segments of these
copolyesters have molecular weights of about 350 to 6000, and
preferably about 600 to 3000. Preferably the long chain glycols
have melting points of less than about 75.degree. C.
The chemical structure of the long chain polymeric part of the long
chain glycol is not critical. Any substituent groups which do not
interfere with the polymerization reaction to form the copolyester
can be present. Thus, the chain can be a single divalent acyclic,
alicyclic, or aromatic hydrocarbon group, poly(alkylene oxide)
group, polyester group, a combination thereof, or the like. Any of
these groups can contain substituents which do not interfere to any
substantial extent with the polymerization to form the copolyester
used in accordance with this invention. The hydroxy functional
groups of the long chain glycols ued to prepare the copolyesters
should be terminal groups to the extent possible.
Suitable long chain glycols which can be used in preparing the soft
segments of the copolymers include poly(alkylene ether) glycols in
which the alkylene groups are of 2 to 9 carbon atoms such as
poly(ethylene ether) glycols, poly( 1,2- and 1,3-propylene ether)
glycol, poly( 1,2-butylene ether) glycol, poly(tetramethylene
ether) glycol, poly(pentamethylene ether) glycol,
poly(hexamethylene ether) glycol, poly(heptamethylene ether)
glycol, poly(octamethylene ether) glycol, poly(nonamethylene ether)
glycol, and random or block copolymers thereof, for example,
glycols derived from ethylene oxide and 1,2-propylene oxide.
Glycol esters of poly(alkylene oxide) dicarboxylic acids can also
be used as the long chain glycol. These glycol esters can be added
to the polymerization reaction or can be form in situ by the
reaction of a dicarboxymethyl acid of poly(alkylene oxide) such as
HOOCCH.sub.2 (OCH.sub.2 CH.sub.2 CH.sub.2 CH.sub.2).sub.x OCH.sub.2
COOH (x is 2 to 90) with the low molecular weight diol, which is
always present in a stoichiometric excess. The resulting
poly(alkylene oxide) ester glycol then polymerizes to form G units
having the structure --DOOCCH.sub.2 (OCH.sub.2 CH.sub.2 CH.sub.2
CH.sub.2).sub.x OCH.sub.2 COOD--(x is 2 to 90) in which each diol
cap (D) may be the same or different depending on whether more than
one diol is used. These dicarboxylic acids may also react in situ
with the long chain glycol, in which case a material is obtained
having a formula the same as above except that the D's are replaced
by G's, the polymeric residue of the long chain glycol. The extent
to which this reaction occurs is quite small, however, since the
low molecular weight diol is present in considerable excess.
Polyester glycols can also be used as the long chain glycol. In
using polyester glycols, care must generally be exercised to
control the tendency to interchange during melt polymerization.
Certain sterically hindered polyesters, e.g., poly(
2,2-dimethyl-1,3-propylene adipate), poly(
2,2-dimethyl-1,3-propylene/2-methyl-2-ethyl-1,3-propylene
2,5-dimethylterephthalate),
poly(2,2-dimethyl-1,3-propylene/2,2-diethyl-1,3-propylene,
1,4-cyclohexanedicarboxylate) and
poly(1,2-cyclohexylenedimethylene/2,2-dimethyl-1,3-propylene,
1,4-cyclohexanedicarboxylate) can be utilized under normal reaction
conditions, and other more reactive polyester glycols can be used
if proper reaction conditions, including a short residence time,
are employed.
Suitable long chain glycols also include polyformals prepared by
reacting formaldehyde with glycols such as pentamethylene glycol or
mixtures of glycols such as a mixture of tetramethylene and
pentamethylene glycols. Polythioether glycols also provide useful
products. Polybutadiene and polyisoprene glycols, copolymers of
these, and saturated hydrogenation products of these materials are
also satisfactory long chain polymeric glycols. In addition, the
glycol esters of dicarboxylic acids formed by oxidation of
polyisobutylene-diene copolymers are useful raw materials. The
preferred long chain glycols are poly(alkylene ether) glycols and
glycol esters of poly(alkylene oxide) dicarboxylic acids.
Butanediol is used in the preparation of the hard segments of
preferred copolyesters. The term "butanediol", as used herein,
should be construed to include equivalent ester-forming derivatives
such as tetrahydrofuran or butanediacetate.
The polytetramethylene ether glycols used to prepare the soft
segments of these copolyesters have molecular weights of about 600
to 3500, and preferably about 600 to 2100.
The relative molecular weight of the segmented copolyester is
expressed herein in terms of melt index, which is an empirical
measurement of inverse melt viscosity. The segmented copolyesters
should have a melt index of less than about 150, less than about 30
for the soft copolyesters, in order to provide useful compositions.
The lower melt indices provide compositions having superior
pressure sensitive properties. The melt indices specified herein
are determined by the American Society for Testing and Materials
(herein abbreviated "ASTM") test method D 1238-65T using Condition
E at 190.degree. C. with a 2160 gram load.
The segmented copolyester, which is a substantially carboxyl free
copolymer, in one embodiment, has a melting point of at least about
125.degree. C. and preferably a melting point of at least about
140.degree. C. The soft copolyesters have a melting point of about
90.degree. to 130.degree. C. The high melting segmented
copolyesters used herein maintain their high melting
characteristics when blended with low molecular weight
thermoplastic resins in accordance with this invention.
The high melting point of the segmented copolyester is obtained by
providing the polyester with crystallizable short chain ester
segments. Crystallinity in the short chain ester segments is
increased by the use of more linear and symmetrical diacid
illustrated with aromatic diacids. By "linear" aromatic diacid is
meant a diacid in which each of the bonds between the carboxyl
carbons and their adjacent carbons fall on a straight line drawn
from one carboxyl carbon to the other. By "symmetrical" aromatic
diacid is meant a diacid which is symmetrical with respect to a
center line drawn from one carboxyl carbon to the other. For
example, repeating ester units such as tetramethylene terephthalate
give an especially high melting short chain ester segment. On the
other hand, when a non-linear and unsymmetrical aromatic diacid,
such as isophthalic acid, is added to crystallizable short chain
ester segments, their melting point is depressed. Small amounts of
isophthalic acid are, however, very useful for controlling the
melting point and improving the compatibility of segmented
copolyesters with low molecular weight thermoplastic resins. In
preparing the harder copolyesters aliphatic dibasic acids should be
avoided since they give low melting or non-crystalline short chain
ester segments.
The melting points specified herein are determined by differential
thermal or thermomechanical analysis. In thermal analysis the
melting point is read from the position of the endotherm peak in a
thermogram when the sample is heated from room temperature at the
range of 10.degree. C./min. The details of this method are
described in many publications, for example, by C. B. Murphy in
Differential Thermal Analysis, R. C. Mackenzie, Editor, Volume I,
Pages 643 to 671, Academic Press, New York, 1970. In
thermomechanical analysis the melting point is determined by
measuring penetration of a penetrometer type probe into a polymer
sample at 10 grams load with the temperature programmed at
5.degree. C./min. The details of this method are described in many
publications, for example, in Du Pont Technical Literature for
Model 941 Thermomechanical Analyzer, Du Pont Co., Wilmington,
Delaware, Oct. 1, 1968.
Inherent viscosity of the segmented copolyester is determined by
standard techniques, 0.1 g./100 ml. m-cresol at 30.degree. C. The
inherent viscosity of the copolyesters ranges from 1.0 to 1.7,
preferably 1.4 to 1.6, and more preferably 1.5.
The number-average molecular weight (Mn) of the copolyester of the
above viscosities ranges from 10,000 to 50,000, preferably 20,000
to 30,000, and more preferably 25,000.
The acid number of the segmented copolyester is determined by
titrating a gram of copolyester with KOH and is the number of
milligrams of KOH necessary to neutralize the gram of copolyester.
The acid number of the copolyester is less than 3.0, preferably
less than 2.0.
Preferred segmented copolyesters are those in which the aromatic
dicarboxylic acid is of 8 to 16 carbon atoms, the low molecular
weight diol is aliphatic diol of 2 to 8 carbon atoms, the long
chain glycol is poly(alkylene ether) glycol in which the alkylene
group is of 2 to 9 carbon atoms, the short chain ester units amount
to about 30 to 65 percent by weight of the copolyester, the long
chain ester units amount to about 35 to 70 percent by weight of the
copolyester, and the copolyester has a melt index of less than
about 50, a melting point of at least about 140.degree. C., an
inherent viscosity of about 1.4 to 1.6 and an acid number of 1 to
less than 2.
The copolyesters prepared from terephthalic acid, or a mixture of
terephthalic and isophthalic acids, 1,4-butanediol and
polytetramethylene ether glycol having a molecular weight of about
600 to 3000 are particularly preferred in the compositions of this
invention. The raw materials are readily available, and the
adhesive and coating properties of compositions obtained from such
polymers are outstanding.
The copolyesters used in the compositions of this invention can be
made by conventional condensation polymerization procedures, as for
example, in bulk or in a solvent medium which dissolves one or more
of the monomers. They are conveniently prepared by a conventional
ester interchange reaction. A preferred procedure involves heating,
for example, the dimethyl ester of terephthalic acid, or a mixture
of terephthalic and isophthalic acid, with a long chain glycol
which may be polytetramethylene ether glycol and an excess of a
short chain diol which may be butanediol in the presence of a
catalyst at 150.degree. to 260.degree. C., followed by distilling
off the methanol formed by the interchange. Heating is continued
until methanol evolution is complete. Depending on the temperature,
catalyst and diol excess, this polymerization is complete within a
few minutes to a few hours. This procedure results in the
preparation of a low molecular weight prepolymer which can be
converted to the high molecular weight segmented copolyester of
this invention.
These prepolymers can also be prepared by a number of alternate
esterification or ester interchange processes. For example, the
long chain glycol can be reacted with a high or low molecular
weight short chain ester homopolymer or copolymer in the presence
of catalyst until randomization occurs. The short chain ester
homopolymer or copolymer can be prepared by ester interchange from
either the dimethyl esters and low molecular weight diols, as
above, or from the free acids with the diol acetates.
Alternatively, the short chain ester copolymer can be prepared by
direct esterification from appropriate diacids, anhydrides, or acid
chlorides, for example, with diols or by other processes such as
reaction of the diacids with cyclic ethers or carbonates. Obviously
the prepolymer can also be prepared by carrying out these processes
in the presence of the long chain glycol.
The resulting prepolymer is then converted to the high molecular
weight segmented copolyester by distillation of the excess of low
molecular weight diol. Best results are usually obtained if this
final distillation is carried out at less than 1 mm. pressure and
240.degree.-260.degree. C. for less than 2 hours in the presence of
an antioxidant such as sym-di-beta-naphthyl-p-phenylenediamine or
1,3,5-trimethyl-2,4,6-tris[ 3,5-ditertiarybutyl-4-hydroxybenzyl]
benzene.
Most practical polymerization techniques rely upon ester
interchange to complete the polymerization reaction. In order to
avoid excess hold times at high temperatures with possible
irreversible thermal degradation, it is advantageous to employ a
catalyst for the ester interchange reaction. While a wide variety
of catalysts can be used, organic titanates such as tetrabutyl
titanate, used alone or in combination with magnesium or zinc
acetates, are preferred. Complex titanates, such as
Mg[HTi(OR).sub.6]2 (R ranges from 2 to 5 carbon atoms), derived
from alkali or alkaline earth metal alkoxides and titanate esters
are also very effective. Inorganic titanates such an lanthanum
titanate, calcium acetate/antimony trioxide mixtures and lithium
and magnesium alkoxides are representative of other catalysts which
can be used.
While these condensation polymerizations are generally run in the
melt without added solvent, it is sometimes advantageous to run
them in the presence of inert solvent in order to facilitate
removal of volatile products at lower than usual temperatures. This
technique is especially valuable during prepolymer preparation, for
example, by direct esterification. However, certain low molecular
weight diols, for example, butanediol in terphenyl, are
conveniently removed during high polymerization by azeotropic
distillation. Other special polymerization techniques, for example,
interfacial polymerization of bisphenol with bisacylhalides and
bisacylhalide capped linear diols, may prove useful for preparation
of specific polymers.
The processes described above can be run both by batch and
continuous methods. The preferred method for continuous
polymerization, namely, ester interchange with a prepolymer, is a
well established commercial process.
In addition to the segmented copolyester, the compositions of this
invention contain one or more low molecular weight thermoplastic
resins which form compatible mixtures with the segmented
copolyester, are thermally stable at about 150.degree. C., and have
melt viscosities of less than about 10,000 centipoises at
200.degree. C.
The term "thermoplastic resin", as used throughout the
specification and claims, is intended to include heat softenable
resins, both natural and synthetic, as well as waxy types of
materials.
By the term "compatible" it is meant that there is no separation
into distinct layers between the segmented copolyester and the low
molecular weight resin or resins at the copolyester melt
temperature. In some cases this compatibility is achieved in blends
of multicomponent resins even though one of the low molecular
weight thermoplastic resin components may not be compatible with
the segmented copolyester alone.
By the phrase "thermally stable", it is meant that there is no
significant permanent alteration in the properties of the resin
after heating at the specified temperature for one hour in the
presence of air. The melt viscosities specified herein are measured
with a Brookfield viscometer by ASTM test method D 1824-66 at
elevated temperatures as indicated.
Suitable low molecular weight thermoplastic resins include
hydrocarbon resins, bituminous asphalts, coal tar pitches, rosins,
rosin based alkyd resins, phenolic resins, chlorinated aliphatic
hydrocarbon waxes, chlorinated polynuclear aromatic hydrocarbons,
and mixtures thereof.
The term "hydrocarbon resins" refers to hydrocarbon polymers
derived from coke-oven gas, coal-tar fractions, cracked and deeply
cracked petroleum stocks, substantially pure hydrocarbon feeds, and
turpentines. Typical hydrocarbon resins include coumarone-indene
resins, petroleum resins, styrene polymers, cyclopentadiene resins,
and terpene resins. These resins are fully described in the
Kirk-Othmer "Encyclopedia of Chemical Technology", Second Edition,
1966, Interscience Publishers, New York, Volume 11, Pages 242 to
255.
The term "coumarone-indene resins" refers to hydrocarbon resins
obtained by polymerization of the resin formers recovered from
coke-oven gas and in the distillation off coal tar and derivatives
thereof such as phenolmodified coumarone-indene resins. These
resins are fully described in the Kirk-Othmer Encyclopedia, supra,
Volume 11, Pages 243 to 247.
The term "petroleum resins" refers to hydrocarbon resins obtained
by the catalytic polymerization of deeply cracked petroleum stocks.
These petroleum stocks generally contain mixtures of resin formers
such as styrene, methyl styrene, vinyl toluene, indene, methyl
indene, butadiene, isoprene, piperylene and pentylenes. These
resins are fully described in the Kirk-Othmer Encyclopedia, supra,
Volume 11, Pages 248 to 250. The so-called "polyalkylaromatic
resins" fall into this classification.
The term "styrene polymers" refers to low molecular weight
homopolymers of styrene as well as copolymers containing styrene
and other comonomers such as alpha-methyl-styrene, vinyl toluene,
butadiene, etc.
The term "vinyl aromatic polymers" refers to low molecular weight
homopolymers of vinyl aromatic monomers such as styrene, vinyl
toluene, and alphamethyl styrene, copolymers of two or more of
these monomers with each other, and copolymers containing one or
more of these monomers in combination with other monomers such as
butadiene, and the like. These polymers are distinguished from
petroleum resins in that they are prepared from substantially pure
monomer.
The term "cyclopentadiene resins" refers to cyclopentadiene
homopolymers and copolymers derived from coal tar fractions or from
cracked petroleum streams. These resins are produced by holding a
cyclopentadiene-containing stock at elevated temperature for an
extended period of time. The temperatures at which it is held
determines whether the dimer, trimer, or higher polymer is
obtained. These resins are fully described in the Kirk-Othmer
Encyclopedia, supra, Volume 11, Pages 250 and 251.
The term "terpene resins" refers to polymers of terpenes which are
hydrocarbons of the general formula C.sub.10 H.sub.16 occurring in
most essential oils and oleoresins of plants, and phenol-modified
terpene resins. Suitable terpenes include alpha-pinene,
beta-pinene, dipenetene, limonene, myrcene, bornylene, camphene,
and the like. These products occur as by-products of coking
operations of petroleum refining and of paper manufacture. These
resins are fully described in the Kirk-Othmer Encyclopedia, supra,
Volume 11, Pages 252 to 254.
The term "bituminous asphalts" is intended to include both native
asphalts and asphaltites such as Gilsonite, Glance pitch and
Grahanite. A full description of bituminous asphalts can be found
in Abraham's "Asphalts and Allied Substances", 6th Edition, Volume
1, Chapter 2, Van Nostrand Co., Inc., particularly Table III on
Page 60.
The term "coal tar pitches" refers to the residues obtained by the
partial evaporation or distillation of coal tar obtained by removal
of gaseous components from bituminous coal. Such pitches include
gas-works coal tar pitch, coke-oven coal tar pitch, blast-furnace
coal tar pitch, producer-gas coal tar pitch, and the like. These
pitches are fully described in Abraham's "Asphalts and Allied
Substances", supra, particularly Table III on Page 61.
The term "rosins" refers to the resinous materials that occur
naturally in the oleoresin of pine trees, as well as derivatives
thereof including rosin esters, modified rosins such as
fractionated, hydrogenated, dehydrogenated and polymerized rosins,
modified rosin esters and the like. These materials are fully
described in the Kirk-Othmer Encyclopedia, supra, Volume 17, Pages
475 to 505.
The term "rosin based alkyd resins" refers to alkyd resins in which
all or a portion of the monobasic fatty acid is replaced by rosin
(a mixture of diterpene resin acids and non-acidic components).
Unmodified alkyd resins are polyester products composed of
polyhydric alcohol, polybasic acid and monobasic fatty acid. Rosin
based alkyd resins are described in the Kirk-Othmer Encyclopedia,
supra, Volume 1, Pages 851, 865 and 866.
The term "phenolic resins" refers to the products resulting from
the reaction of phenols with aldehydes. In addition to phenol
itself, cresols, xylenols, p-tert.-butylphenol, p-phenylphenol and
the like may be used as the phenol component. Formaldehyde is the
most common aldehyde, but acetaldehyde, furfuraldehyde and the like
may also be used. These resins are fully described in the
Kirk-Othmer Encyclopedia, supra, Volume 15, Pages 176 to 207.
The term "chlorinated aliphatic hydrocarbon waxes" refers to those
waxes which are commonly called "chlorinated waxes" such as
chlorinated paraffin waxes. These waxes typically contain about
30-70 percent by weight of chlorine.
The term "chlorinated polynuclear aromatic hydrocarbons" refers to
chlorinated aromatic hydrocarbons containing two or more aromatic
rings such as chlorinated biphenyls, terphenyls, and the like, and
mixtures thereof. These materials typically contain 30 to 70
percent by weight of chlorine.
The compositions of this invention contain about 1 to 99 percent by
weight, preferably 5 to 95 percent by weight, of thermoplastic
segmented copolyester elastomer and about 1 to 99 percent by
weight, preferably 5 to 95 percent by weight, of low molecular
weight thermoplastic resin. More preferably, the composition
contains about 20 to 60 percent by weight of elastomer and about 40
to 80 percent by weight of resin.
Typically the compositions of this invention contain more than one
low molecular weight thermoplastic resin. For example, low
molecular weight vinyl aromatic polymers, e.g., styrene polymers,
have been found to lower the melt viscosity of these compositions
without substantially lowering the softening point. Since low melt
viscosity contributes improved wetting by the composition of the
surface of the substrate, which results in better adhesion, many
useful compositions will contain some vinyl aromatic polymer. Vinyl
aromatic polymers such as styrene are also useful for increasing
the compatibility of other resins with the segmented copolyester.
Coumarone-indene resins of high softening point have been found to
give strength to the compositions. Phenol-modified coumarone-indene
resins have been found to have the effect of lowering the softening
point of the compositions. In fact, the effect of phenol-modified
coumarone-indene resins on the melting point is so great that the
desired melting point is generally achieved by the addition of only
a small amount of this resin. Any combination of these dried
properties can be achieved by mixing two or more low molecular
weight thermoplastic resins with the copolyester in a proper
proportion. The low molecular weight thermoplastic resins also have
the effect of lowering the cost of the composition.
In order to prevent loss in properties, such as viscosity, which
affect the adhesion characteristics of the thermoplastic
compositions prepared from a segmented copolyester and at least one
compatible thermoplastic resin, it is necessary that to the
segmented copolyester or to the thermoplastic composition, as the
case may be, there is added 0.05 to 3.0 percent by weight,
preferably 0.1 to 1.0 percent by weight, of segmented copolyester
or 0.1 to 4.0 percent by weight, preferably 0.25 to 2.5 percent by
weight, of thermoplastic composition, respectively, of an alkaline
earth oxide such as beryllium, magnesium, calcium, strontium, and
barium oxides. Calcium oxide is preferred.
It has been found that in many adhesive thermoplastic compositions
of thermoplastic segmented copolyester and low molecular weight
thermoplastic resin improved stability is achieved by adding, in
conjunction with the alkaline earth oxide 0.25 to 2.5 percent by
weight of segmented copolyester or 0.1 to 1.0 percent by weight of
thermoplastic composition, respectively, of linear polycarbodiimide
having an average of at least two carbodiimide groups per
molecule.
The linear polycarbodiimide is represented by the formula
wherein R.sub.1, R.sub.2, and R.sub.3 are C.sub.1 -C.sub.12
aliphatic, C.sub.6 -C.sub.15 cycloaliphatic, or C.sub.6 -C.sub.15
aromatic divalent hydrocarbon radicals, and combinations thereof;
X.sub.1 and X.sub.2 are H, ##STR8## where R.sub.4, R.sub.5, and
R.sub.6 are C.sub.1 -C.sub.12 aliphatic, C.sub.5 -C.sub.15
cycloaliphatic and C.sub.6 -C.sub.15 aromatic monovalent
hydrocarbon radicals and combinations thereof and additionally
R.sub.4 or R.sub.5 can be hydrogen; and n is a number of at least
1, preferably 1 to 7. The useful polycarbodiimides have an average
of at least two carbodiimide groups (i.e., two --N.= C = N--
groups) per molecule and an average molecular weight of less than
about 500 per carbodiimide group. These polycarbodiimides can be
aliphatic, cycloaliphatic, or aromatic polycarbodiimides. The terms
aliphatic, cycloaliphatic, and aromatic as used herein indicate
that the carbodiimide group is attached directly to an aliphatic
group, a cycloaliphatic group, or an aromatic nucleus respectively.
For example, these carbodiimides are illustrated by the above
formula wherein R.sub.1, R.sub.2, and R.sub.3 are independently
aliphatic, cycloaliphatic, or aromatic divalent hydrocarbon
radicals and n is at least 1 and preferably 1-7. X.sub.1 and
X.sub.2 and defined as hereinbefore. Polycarbodiimides useful for
the compositions of this invention have more than two
polycarbodiimide groups and thus more than three divalent
hydrocarbon groups (i.e., R.sub.1, R.sub.2, R.sub.3 . . . R.sub.n)
and each of these hydrocarbon groups can be the same or different
from the others so that the polycarbodiimides can have aliphatic,
cycloaliphatic, and aromatic hydrocarbon groups in one
polycarbodiimide molecule.
Polycarbodiimides can be prepared for use in this invention by
well-known procedures. Typical procedures are described in U.S.
Pat. Nos. 3,450,562 to Hoeschele; 2,941,983 to Smeltz; 3,193,522 to
Neumann et al.; and 2,941,966 to Campbell.
Generally, polycarbodiimides are prepared by polymerization of
organic diisocyanates. The isocyanate groups on a diisocyanate
molecule polymerize with isocyanate groups on other diisocyanate
molecules so that the resulting polycarbodiimide molecule is a
linear polymer of organic radicals (i.e., aliphatic,
cycloaliphatic, aromatic, or combinations thereof) linked together
by carbodiimide groups (i.e., --N = C = N--). The degree of
polymerization and the specific diisocyanate determine the
molecular weight of the polycarbodiimide and the average molecular
weight per carbodiimide group.
Many known organic isocyanates can be polymerized to produce
polycarbodiimides useful for stabilized compositions of this
invention. Isocyanates which can be polymerized to produce
preferred aromatic polycarbodiimides include:
tolylene-2,4-diisocyanate,
tolylene-2,6-diisocyanate,
.alpha.,4-tolylene diisocyanate,
1,3- and 1,4-phenylene diisocyanates,
4,4'-methylenebis(phenyl isocyanate),
5-chlorotolylene-2,4-diisocyanate,
1,5-naphthylene diisocyanate,
1,6-hexamethylene diisocyanate,
4,4'-methylenebis(cyclohexyl isocyanate), 1,3- and
1,4-cyclohexylene diisocyanates,
1,3-diisopropylphenylene-2,4-diisocyanate,
1-methyl-3,5-diisopropylphenylene-2,4-diisocyanate,
1,3,5-triethylphenylene-2,4-diisocyanate,
triisopropylphenylene-2,4-(2,6-)diisocyanate.
Diisocyanates, such as tolylene-2,4-diisocyanate or mixtures
thereof with minor amounts of tolylene-2,6-diisocyanate and
4,4'-methylenebis(phenyl isocyanate), can be used to produce
preferred unhindered aromatic polycarbodiimides which have only
partial ortho substitution on the aromatic nuclei to which
polycarbodiimide groups are attached. Diisocyanates such as
triisopropylphenylene-1,3-diisocyanate yield preferred hindered
aromatic polycarbodiimides.
Polymerization of diisocyanates to produce polycarbodiimides of a
given degree of polymerization can be controlled by introducing
agents which will cap the terminal isocyanate groups. These agents
include monoisocyanates and active hydrogen compounds such as
alcohols or amines. Polyisocyanates and other agents which will
produce cross-linking of the polycarbodiimide generally should be
avoided as cross-linking can reduce solubility and lead to blending
problems with the copolyester. Preferably, isocyanate
polymerization should be stopped to produce polycarbodiimides
having average molecular weight in the range of about 600-2500 and
2-8 carbodiimide linkages. Polycarbodiimides in this preferred
range can be readily mixed with copolyester and are sufficiently
nonvolatile to prevent loss by vaporization.
The average number of carbodiimide groups per molecule can be
estimated for a given polycarbodiimide from the proportions of the
reactants employed in its preparation. As described elsewhere, the
degree of polymerization of the polycarbodiimide can be controlled
by employing capping agents. Alternatively, the average number of
carbodiimide groups per molecule in a given polycarbodiimide can be
calculated from its molecular weight (obtained by vapor phase
osmometry or ebulliscopic procedures) and its assay for
carbodiimide groups [determined by the method of Campbell and
Smeltz, J. Org. Chem., 28, 2069-2075 (1963)].
A particularly preferred polycarbodiimide is sold under the
tradename Stabaxol PCD by Mobay Chemical, Pittsburgh,
Pennsylvania.
Additional compounds which can be added, singly or in combination,
with the alkaline earth oxide with or without the presence of
polycarbodiimide, include:
1. 0.25 to 5.0 percent by weight of segmented copolyester or 0.1 to
2.0 percent by weight of thermoplastic composition, respectively,
of a compound taken from the group consisting of hindered phenols,
nitrogen-containing hindered phenols and hindered secondary amines.
Useful hindered phenols include: 2,6-ditertiary-butyl-p-cresol;
4,4'-bis(2,6-ditertiarybutylphenol);
4,4',4"-(2,4,6-trimethyl-5-phenyl) trimethylene) tris
2,6-di-tert.-butyl phenol;
1,3,5-trimethyl-2,4,6-tris[3,5-ditertiarybutyl-4-hydroxybenzyl]
benzene; 4,4'-butylidene bis(6-tertiary-butyl-m-cresol); .alpha.,
.alpha.'-oxybis(2,6-di-tert.-butyl-p-cresol;
2,6-di-tert.-butyl-.alpha.-methoxy-p-cresol; 2,6
bis(5-tert.-butyl-4-hydroxy-m-tolyl) mesitol;
4,4'-methylene-bis(2,6-di-tert.-butyl-phenol);
2,2'-methylene-bis-(6-tert.-butyl-4-methyl) phenol;
4,4'-(tetramethyl-p-phenylene) dimethylene-bis-2,6-di-tert.-butyl
phenol; 2,2',6,6'-tetra-tert.-butyl-p,p' biphenol;
3,5-ditert.-butyl-4-hydroxy benzyl alcohol;
4,4'-isopropylidine-bis-butylated phenol; 2,5-ditert.-butyl
hydroquinone, 2,2'-methylenebis(6-tert-butyl-4-methyl phenol);
2,2'-methylenebis(6-tert-butyl-4-ethyl phenol); 2,2'-methylenebis
[4-methyl-6-(1,1,3,3-tetramethyl)butyl phenol];
4,4'bis(2-tert-butyl-5-methyl phenol) sulfide;
4,4'-butylidene-bis(2-tert-butyl-5-methyl phenol);
2,2'-methylenebis(4,6-dimethyl phenol); 2-tert-butyl-4(4-tert-butyl
phenyl)phenol; 2-tert-butyl-4-phenyl phenol; 2,6-dibenzyl-4-methyl
phenol; 2-benzyl-4-methyl phenol; 2-benzyl-6-tert-butyl-4-methyl
phenol; 2-benzyl-6-tert-butyl-4-ethyl phenol;
2,4-dimethyl-6-(1-methyl-1-cyclohexyl) phenol,
2,6-diisopropyl-4-methyl phenol; 2,4-dimethyl-6-isopropyl phenol;
2-tert-butyl-4,6-dimethyl phenol; 2-tert-butyl-4-methyl phenol;
2-(1,1,3,3-tetra-methyl butyl)-4- methyl phenol; 2,4,6;L -trimethyl
phenol; 2,6-di-tert-butyl-4-methyl phenol;
2,6-di-tert-butyl-4-ethyl phenol; 4-phenyl phenol; 2,6-diisopropyl
phenol; 2,6-di-tert-butyl-4-phenyl phenol;
2,6-di-tert-butyl-4(4-tert-butyl-phenyl)phenol;
2,5-di-tert-butyl-hydroquinone; 2,5-di-tert-amyl hydroquinone, and
alpha-conidendrine. Mixtures of the foregoing may be used. The
preferred hindered phenol is
tetrakis[methylene-3-(3',5'-ditertiary-butyl-4'-hydroxyphenyl)propionate]
methane.
Suitable nitrogen-containing hindered phenols include
2,6-di-tert-butyl-.alpha.-dimethylamino-p-cresol;
4-hydroxydodecanalide; 4-hydroxy butyranalide; p-butylaminophenol;
2,4-bis[n-octylthio]-6[4'-hydroxy-3,5'ditertiary butyl
anilio]-1,3,5-triazine. A preferred compound is CHA 1014 sold by
Ciba-Geigy, Ardsley, New York, described in Example 40.
Useful secondary amine compounds are 4,4'-dioctyl diphenylamine;
diethyl dinonyl diphenylamine; 4-isopropoxy diphenylamine;
N,N'-diphenyl-1,2-propanediamine; octylated diphenylamine;
p-isopropoxydiphenylamine; phenyl-.alpha.-naphthylamine; phenyl
.beta.-naphthylamine; N,N'diphenylethylene diamine;
N',N'-di-o-tolyethylene diamine; N',N'-diphenyl-1,2-propylene
diamine; N,N'-diphenyl-p-phenylene diamine. A preferred secondary
amine is N,N'-di-2-naphthylparaphenylenediamine.
2. 0.25 to 5.0 percent by weight of segmented copolyester or 0.1 to
2.0 percent by weight of thermoplastic composition, respectively,
of a dialkylthiodipropionate ester of 12 to 18 carbon atoms. Useful
esters of this type include preferably distearylthiodipropionate
and dilaurylthiodipropionate.
3. 0.25 to 5.0 percent by weight of segmented copolyester or 0.1 to
2.0 percent by weight of thermoplastic composition, respectively,
of a phosphorous acid ester of the formula ##STR9## where R.sub.1,
R.sub.2 and R.sub.3 are C.sub.1 to C.sub.18 aliphatic, C.sub.6 to
C.sub.15 aromatic and combinations thereof. Useful phosphorous acid
esters include trioctyl phosphite, pentol triphosphite, trilauryl
phosphite, triisodecyl phosphite, diphenyl isooctyl phosphite,
(2-ethylhexyl)-octyl-phenyl phosphite, tris(2-ethylhexyl)
phosphite, triphenyl phosphite, trimethyl phosphite, triethyl
phosphite, diphenyl-p-(.alpha.-methylbenzyl) phenyl phosphite,
tributyl phosphite, phenyl-di(isodecyl) phosphite,
tri-tetrahydrofurfuryl phosphite, di(isodecyl)-2-ethylphenyl
phosphite, tri-secondarybutyl phosphite, tri-tertiarybutyl
phosphite, trihexyl phosphite, tricyclohexyl phosphite,
diphenyl-lauryl phosphite, phenyl-dilauryl phosphite, trinaphthyl
phosphite. A preferred compound is trinonylphenyl phosphite sold by
Argus Chemical Corp., Brooklyn, New York under the tradename Mark
1178.
Each of the compounds (1), (2) and (3) are compatible with each
other and with calcium oxide and the polycarbodiimide compound. By
compatible in this context is meant that the various compounds
retain their individual indentity when mixed and do not chemically
combine with one another.
The properties of the compositions of this invention can be
modified by the incorporation of various conventional inorganic
fillers such as wood flour, silicates, silica gel, alumina, clays,
chopped fiberglass, titanium dioxide, barium sulfate, carbon black,
etc. In general, fillers have the effect of increasing the melt
viscosity and the modulus or stiffness of the composition at
various elongations.
The properties of the compositions of this invention can be further
modified by the incorporation of thermally stable thermoplastic
polymers of ethylenically unsaturated monomers including
homopolymers of vinyl esters such as vinyl acetate, copolymers of
these vinyl esters with other vinyl monomers such as ethylene,
vinyl chloride and the like, and polymers of alkyl acrylates and
methacrylates, or thermally stable condensation polymers such as
polyesters and polyamides, and the like. For example, the addition
of a copolymer of ethylene and vinyl acetate often increases the
tackiness of pressure sensitive adhesive compositions of this
invention. These modifying polymers typically have melt viscosities
above about 10,000 centipoises at 200.degree. C. and thus are not
low molecular weight thermoplastic resins as defined herein.
The compositions can also be colored by the addition of organic or
inorganic pigments or organic dyes where their effect is desired.
Suitable inorganic pigments include rutile and anatase titanium
dioxides, aluminum powder, cadmium sulfides and sulfo-selenides,
lead antimonate, mercury cadmiums, chromates of nickel, tin and
lead, ceramic greens such as chromium, cobalt, titanium and nickel
oxides, ceramic blacks such as chromium, cobalt and iron oxides,
carbon black, ultramarine blue, and the like. Suitable organic
pigments include phthalocyanine blues and greens, quinacridones,
and the like. Suitable dyes include disperse dyes such as Colour
Index Disperse Blues 59, 63 and 64. Optical brightner such as
"Uvitex" CF, sold by Ciba Corp., and "Tinopal" AN, sold by Geigy
Chemical Corp., may also be incorporated where their effect is
desired.
Plasticizers including phthalate esters such as dioctyl phthalate,
and aryl phosphates such as tricresyl phosphate, and substituted
sulfonamides such as N-cyclohexyl-p-toluene-sulfonamide and the
like, may be added for applications where their effect is desired.
Flame retardant additives, such as zinc borate, antimony trioxide,
tris(2,3-dichloropropyl) phosphate, tris(2,3-dibromopropyl)
phosphate, chlorinated waxes, and the like may be added, if
desired. Other minor additives such as surfactants or lubricants
may also be added.
One of the important advantages of the thermoplastic compositions
of this invention is that the copolyesters and the low molecular
weight thermoplastic resins are easy to blend together due to the
relatively low melt viscosity of these compositions at elevated
temperatures as compared to compositions of the prior art having
comparable bond strength. The components of the compositions of
this invention can be blended by variously well-known procedures
such as, for example, blending in molten form, blending in a
solvent, or mixing aqueous dispersions of the components. Blending
in the melt may be carried out by first melting the stabilized
segmented copolyester and then adding low molecular weight
thermoplastic resin to the melt, by first melting the low molecular
weight thermoplastic resin and then adding stabilized segmented
copolyester to the melt, or by first blending the segmented
copolyester and the low molecular weight thermoplastic resin
together in finely divided form and then melting the blend, for
example, on a hot roller mill or by simultaneously feeding the
components to an extruder. The alkaline earth oxide stabilizer
compound, with or without optional components, can be present prior
to blending or can be added with the other components individually
or as a mixture.
One method of mixing the alkaline earth oxide stabilizer compound
or mixture thereof with the segmented copolyester is to take an
amount of the copolyester and mix in the amount of alkaline earth
oxide stabilizer and any optional additives described above either
individually or as a mixture.
In addition to these blending procedures, it is also possible to
take the copolyester while it is still molten, and blend solid,
premelted or liquid low molecular weight thermoplastic resin with
it. The stabilizer compound or mixture thereof as well as other
ingredients such as antioxidants, fillers, plasticizers, and the
like can also be added at this time. This blending process can be
carried out with an in-line mixer or with a separate mixing vessel,
and has the advantage that it does not require isolation of the
copolyester.
The thermoplastic compositions of this invention can also be
blended by dissolving the segmented copolyester and the low
molecular weight thermoplastic resin in a solvent. Suitable
solvents for preparing these solutions include chlorinated
hydrocarbons such as methylene chloride, chloroform,
trichloroethylene, solvent mixtures such as mixtures of
trichloroethylene and isopropanol, and the like.
Aqueous dispersions of the thermoplastic compositions of this
invention can be prepared by dissolving the segmented copolyester
and the low molecular weight thermoplastic resin together in a
suitable water-immiscible organic solvent, emulsifying the organic
solvent containing the segmented copolyester and the low molecular
weight thermoplastic resin in water, and removing the organic
solvent as described by Funck and Wolff in U.S. Pat. No. 3,296,172.
Dispersions can also be prepared by dissolving the segmented
copolyester in a suitable water-immiscible organic solvent,
dissolving the low molecular weight thermoplastic resin in a
different water-immiscible organic solvent, emulsifying each
organic solvent solution in water, removing the organic solvent
from each emulsion, thereby forming separate dispersions, and
mixing the dispersions together in proper amounts.
Compositions containing about 50 percent by weight or more of
segmented copolyester can be used as concentrates for further
compounding with the same or other low molecular weight
thermoplastic resins and modifiers, as well as being useful as
such. Such concentrated compositions have the advantage of being
processable with additional components at lower temperatures and
shear requirements than the segmented copolyester itself. For
example, a mixture containing an equal weight of segmented
copolyester and low molecular weight, thermoplastic styrene
homopolymer is typically blended at a minimum temperature of about
170.degree. C. However, additional low molecular weight
thermoplastic resins can be mixed with this concentrate at a
minimum blending temperature of about 140.degree. C. Moreover,
additional low molecular weight thermoplastic resins which have
limited compatibility with the segmented copolyester alone tend to
be more compatible with such concentrates.
The compositions of this invention are useful as adhesives and as
coating compositions. These compositions can be applied in the form
of a dry blend, a solution, an aqueous dispersion, or in molten
form. The softer compositions are useful as pressure sensitive
adhesives which can be applied in the form of a solution, an
aqueous dispersion, or in molten form. The method of application
does not appreciably affect the performance of the composition.
Conventional application equipment can be used for applying the
compositions of this invention in the various forms. For
application of solutions or dispersions, as in the case of heat
sealing and pressure sensitive adhesives, various known application
techniques can be used including brushing, dipping, roll coating,
wirewound rod application, doctoring, printing, and the like.
Spraying or curtain coating techniques are also applicable to these
forms of the compositions.
For application of these compositions in the melt form, dipping,
roll coating, calendaring, curtain coating, extruding, hot
spraying, and other hot melt application techniques can be used.
Standard equipment can be used if the adhesive composition in the
molten state is within the inherent viscosity range set forth
above. Powder coatings of appropriate nontacky compositions can
also be applied by known fluidized bed techniques, electrostatic
powder spray application, or plasma spraying.
In using the compositions of this invention as hot melt adhesives,
the joining step can be accomplished by applying the molten
composition to one surface, bringing the other surface into contact
with the molten composition, and allowing the bond to cool.
Coatings of these compositions can be bonded to other surfaces or
themselves by heat or solvent activation of the coating, and
contacting the activated coating with the second surface and
allowing the bond to cool or the solvent to evaporate. Heat
activation of the coating is typically carried out in an oven or
using an infrared lamp. Simultaneous application of heat and
pressure, or heat sealing, can be used with these compositions to
accomplish bonding. High frequency dielectric and ultrasonic waves
can also be used to activate these compositions to effect
bonding.
The compositions of this invention are characterized by an
outstanding combination of properties. These compositions have
demonstrated excellent adhesion to many substrates including
difficulty adherable substrates such as polypropylene. The
compositions containing up to 50 percent by weight of segmented
copolyester typically have 180.degree. peel strengths higher than
about 0.2 pounds per linear inch with a variety of substrates. They
have high temperature bond strengths, for example, as shown by
failure temperatures higher than about 70.degree. C. in the
adaptation of the WPS-68 test described below. They have good low
temperature flexibility, that is, resistance to breakage on impact,
and a minimum elongation of 50 percent at room temperature. They
have tensile strengths higher than 200 psi. at room temperature.
The softer compositions are characterized by an outstanding
combination of pressure sensitive adhesive properties. Performance
of a pressure sensitive adhesive is gauged by measurement of both
peel and shear adhesion to standard substrates. Tack is also an
important property. Compositions described herein display
180.degree. peel values as high as 4-5 lbs./in. and 90.degree.
quick stick values as high as 3.5-4.0 lbs./in. They have good shear
strength (300+ hrs. at RT) and similarly exhibit good high
temperature bond strength (as high as 185 min. at 70.degree. C.).
Tack levels are high (1-6 inches) as measured by rolling ball tack
or by Polyken probe tack measurement (as high as 950 g.). A good
balance of all the properties mentioned above can be obtained by
proper formulation, or any one property can be specifically
enhanced by formulation.
Due to the presence of the stabilizing mixture the compositions
have good pot life when heated to 170.degree. to 200.degree. C. for
extended periods of time within the period of 12 to 24 hours.
Generally the viscosity will vary only .+-. 25 percent in 12 hours
at 190.degree. C.
The compositions containing up to 50 percent by weight of segmented
copolyester are particularly useful as hot melt adhesives in a wide
variety of adhesive use applications such as edge banding and
surface lamination, for example, in furniture manufacture, vinyl
lamination, sole attachment and box-toe construction in shoe
assembly, and as pressure sensitive adhesives for carpet tiles,
vinyl tiles, premium labels, tapes, decals, decorative molding of
wood or plastic, and the like.
Compositions containing about 50 percent or more by weight of
thermoplastic segmented copolyester are particularly useful in the
preparation of molded, extruded, and dipped goods, coatings,
binders, extruded adhesives, sealants, and the like. Films can be
prepared from these compositions by molding, extrusion and
calendaring techniques. These compositions typically contain about
50 to 99 percent by weight of segmented copolyester and about 1 to
50 percent by weight of low molecular weight thermoplastic resin.
Preferably they contain about 50 to 95 percent by weight of
segmented copolyester and about 5 to 50 percent by weight of low
molecular weight thermoplastic resin.
Compositions containing these higher concentrations of segmented
copolyester can also be used as concentrates for further
compounding with the same or other low molecular weight
thermoplastic resins and modifiers, as well as being useful as
such. Such concentrated compositions have the advantage of being
processable with additional components at lower temperatures and
shear requirements than the segmented copolyester itself. For
example, a mixture containing an equal weight of segmented
copolyester and low molecular weight, thermoplastic styrene
homopolymer is typically blended at a minimum temperature of about
170.degree. C. However, additional low molecular weight
thermoplastic resins can be mixed with this concentrate at a
minimum blending temperature of about 140.degree. C. Moreover,
additional low molecular weight thermoplastic resins which have
limited compatibility with the segmented copolyester alone tend to
be more compatible with such concentrates.
EXAMPLES OF THE INVENTION
The following examples wherein the percentages and parts are by
weight illustrate the invention.
In the examples, the viscosity values were determined by charging
the segmented copolyester or blend into a Brookfield Thermosel
System, manufactured by Brookfield Engineering Laboratories,
Stoughton, Massachusetts, equipped with a RVT model viscometer, No.
27, 28 or 29 spindle, preheated at 190.degree.-195.degree. C. and a
proportional temperature controller, Model 63A. To insure accuracy
of temperature the system was calibrated prior to use with high
temperature viscosity standard fluid available from Brookfield
Engineering Laboratories. Desired temperature is maintained by use
of the proportional temperature controller. As soon as the
copolyester or blend was molten the spindle was lowered into the
melt and the time recorded. The viscometer was run at 0.5 to 2.5
rpm. The rpm in the examples below is 1.0 unless stipulated.
Initial viscosity is the value obtained approximately 30 minutes
after start of the viscometer which is generally sufficient to
obtain equilibrium of viscosity, and at intervals for a maximum of
12 to 24 hours.
Ring and ball softening points of the blends can be determined by
ASTM method E 28-67. Tensile properties can be determined with
compression molded samples using ASTM test method D 1708-66.
High temperature bond failure temperatures were determined by an
adaptation of test method WPS-68 described by W. Schneider and D.
Fabricius in the German periodical "Adhaesion", January, 1969,
Pages 28-37. This test measures the temperature at which the bond
between a particle board and wood veneer or plastic bond fails
under a constant shear stress of 125 g./cm..sup.2 when the
environmental temperature is raised by a 10.degree. C. increment
every hour.
Test methods used in pressure sensitive adhesive evaluations are
procedures developed by the Specifications and Technical Committee
of the Pressure Sensitive Tape Council (PSTC) as published in their
manual entitled "Test Methods for Pressure Sensitive Tapes-Fifth
Edition" and the Polyken Probe Tack Test. The 180.degree. Peel
Adhesion Test (PSTC-1); 90.degree. Peel Quick Stick Adhesion Test
(PSTC-5); Rolling Ball Tack Test (PSTC-6); and Shear Adhesion Test
(PSTC-7) are described in assignee's Hoh and Reardon application
U.S. Ser. No. 439,848, filed Feb. 6, 1974.
Polyken Probe Tack Test
A Polyken Probe Tack Tester, Model No. TMI 80-2, was used for this
test. This tester is a device for measuring the tackiness of
pressure sensitive adhesives, by bringing the flat tip of a probe
into contact with the test specimen at a conrolled rate, contact
pressure, and dwell time, and subsequently breaking the adhesive
bond thus formed, also at a controlled rate. The standard probe is
a 0.5-cm. diameter, 304 stainless steel rod which is mounted by
means of a collet chuck directly on a mechanical force gauge fitted
with a dial indicator.
In these tests, the highly polished end of the probe was used. A
contact pressure of 100 g./cm..sup.2, and a dwell time of 1 sec.
was also used with the probe and sample being brought into contact
and separated at the rate of 1 cm./sec. Further details of this
test are available from the Kendall Company or Testing Machines
Company.
The Shear test is conducted as follows: Thermal testing of the
bonded sample is carried out by suspending it in shear
configuration in a circulating air oven held at 50.degree. C.
(122.degree. F.). A weight of 1.0 lb. is applied to the end of the
melamine strip after the sample has been heated for 0.5 hour. The
temperature of the oven is programmed to increase linearly from
50.degree. C. (122.degree. F.) at a rate of 10.degree. C.
(18.degree. F.) per hour. The failure temperature is recorded when
the weight falls.
The cleavage test is conducted as follows: Samples for this test
are prepared in a manner identical to that for the Shear Test.
Thermal testing of the aged sample is carried out in a circulating
air oven, with the adhesive-bonded area in a horizontal
configuration and the melamine laminate on the bottom. A 1.0 lb.
weight is suspended from the melamine strip 1.0 in. from the edge
of the bonded area. The oven temperature is again programmed
linearly, but this time from room temperature at a rate of
10.degree. C. (18.degree. F.) per hour, and the failure temperature
is taken when the weight falls.
The following procedure is applicable to the Examples. To a 2-liter
resin kettle, equipped with an electric heating mantle and an air
driven stirrer was added the amount of resin(s), stabilizer and
optional components were added (individually or in combination) and
the temperature was raised until the resins were molten. The
segmented copolyester was added and the temperature was increased
to 190.degree.-200.degree. C. with agitation until a uniform
adhesive blend composition was obtained, for example, in the range
of up to 2 hours. When a uniform adhesive composition was obtained,
the mixture was discharged into one-inch deep-Teflon-lined aluminum
trays and was allowed to cool to room temperature. A sample of the
cooled adhesive blend was charged to a thermosel and the viscosity
determined as set forth above.
EXAMPLES 1 to 11
Adhesive blend: 40 percent of a segmented copolyester derived from
31.6 percent terephthalic acid, 9.2 percent isophthalic acid, 16.6
percent butanediol and 42.6 percent poly(tetramethylene ether)
glycol (abbreviated PTMEG hereafter) having a molecular weight of
about 1000, containing 52.6 percent short chain ester units and
having a melting point of 142.degree.-144.degree. C. measured by
differential thermal analysis, a melt index of 5-8 measured at
200.degree. C., an inherent viscosity of about 1.5 and an acid
number of 1.67 and containing 13.0 percent Nevillac Super Hard
resin, an alkylated phenolic modified coumarone-indene resin,
hydroxyl No. 113, ring and ball softening point
90.degree.-100.degree. C., sold by Neville Chemical Co.,
Pittsburgh, Pennsylvania; 13.0 percent Nevillac X-66 resin, an
alkylated phenolic modified coumarone-indene resin, hydroxyl No.
130, softening point 10.degree. C., sold by Neville Chemical Co.,
Pittsburgh, Pennsylvania; 7.0 percent Piccoumaron 410 HL resin, a
polyindene type, highly aromatic, thermoplastic petroleum resin
having ring and ball softening point of about 110.degree. C. and a
melt viscosity of 158 centipoises at 190.degree. C. sold by
Hercules Inc.; and 27.0 percent Barium Sulfate, B.A.R. No. 104 Foam
Grade, sold by IMCO -- Halliburton Co., Houston, Texas.
The adhesive blend and calcium oxide stabilizer compound and other
components indicated in Table 1 were added to the resin kettle and
tested in the thermosel as described above with the viscosity being
determined at 190.degree. C. for the indicated hours.
TABLE 1
__________________________________________________________________________
Stabilizer (%)* Example CaO/Other components Viscosity (1000 cps.)
at 190.degree. C./Hours at 190.degree. C.
__________________________________________________________________________
1 0.25 215/Initial; 180/4; 150/8; 125/12 CaO 2 1.0 220/Initial;
185/8; 170/18 CaO 3 0.25/0.25 260/Initial; 235/4; 210/8; 180/12
CaO/PCD 4 0.50/0.25 264/Initial; 260/2.3; 255/5.3; 255/7.7; 255/11;
215/13 CaO/PCD 5 1.0/0.25 200/Initial; 203/1.5; 211/6.5; 213/11;
205/14.6; 204/17.6 CaO/PCD 6 1.0/0.25/1.0 260/Initial; 264/2.3;
270/4.3; 260/10; 235/16 CaO/PCD/1010 7 1.0/0.25/1.0 235/Initial;
235/4.5; 230/10; 220/16 CaO/PCD/445 8 1.0/0.25/0.5 290/Initial;
295/3; 300/6; 305/12; 285/19.5 CaO/PCD/DSTDP 9 1.0/0.25/1.0
265/Initial; 273/4; 275/9; 274/12; 265/18 CaO/PCD/AGW 10
1.5/0.25/1.0/0.5 380/Initial; 390/2; 395/23 CaO/PCD/1010/DSTDP 11
0.25 200/Initial; 140/8; 100/16 PCD Control None 167/Initial;
149/2; 117.5/4.5; 82.5/8.5; 65/11.5;
__________________________________________________________________________
45/16 *CaO - Calcium Oxide, Reagent Grade sold by Fisher Chemical
Co. PCD - Stabaxol PCD (polycarbodiimide) sold by Mobay Chem. Co.,
Pittsburgh, Pa. 1010 - Irganox 1010, Hindered Phenol Antioxidant
sold by Ciba-Geigy Co. 445 - Naugard 445, Hindered Secondary Amine
Antioxidant sold by Uniroyal AGW - Agerite White, Hindered
Secondary Amine Antioxidant sold by Vanderbilt Co. DSTDP - Naugard
DSTDP, Distearylthiodipropionate sold by Uniroyal.
The cleavage values for Examples 5 and 8 were 95.degree. and
110.degree. C., respectively. The shear value for Example 5 was
146.degree. C.
EXAMPLES 12 to 20
An adhesive blend similar to the blend of Examples 1 to 11 was
prepared except that the Piccoumaron 410 HL resin was replaced by
7.0 percent Atlac 382E polyester resin, a propoxylated bisphenol A
fumarate polyester resin, acid No. 16, softening point
94.degree.-108.degree. C., sold by ICI America, Inc., Wilmington,
Delaware.
The adhesive blend and calcium oxide stabilizer compound and other
components indicated in Table 2 were added to the resin kettle and
tested in the thermosel as described above with the viscosity being
determined at 190.degree. C. for the indicated hours.
TABLE 2
__________________________________________________________________________
Stabilizer (%)* Example CaO/Other components Viscosity (1000 cps.)
at 190.degree. C./Hours at 190.degree. C.
__________________________________________________________________________
12 0.33 267/Initial; 170/7.5; 120/20.5 CaO 13 0.60 294/Initial;
260/4.5; 240/12; 230/22 CaO 14 0.75 275/Initial; 260/5.5; 270/12.5
CaO 15 0.30/0.25 275/Initial; 275/7.5; 200/16 CaO/PCD 16 0.45/0.25
290/Initial; 245/7.5; 180/16 CaO/PCD 17 0.75/0.25 340/Initial;
450/4; 450/11.5; 410/14 CaO/PCD 18 0.75/0.25/1.0 330/Initial;
375/4; 345/9; 315/14 CaO/PCD/445 19 0.75/0.25/1.0/0.5 370/Initial;
466/2.5; 485/7.5; 440/14; 385/20 CaO/PCD/AGW/DSTDP 20
0.75/0.25/1.0/0.5 306/Initial; 390/2.5; 410/715; 385/14; 385/20
CaO/PCD/1010/DSTDP Control None 260/Initial; 200/2.5; 165/4.5;
140/7.5;
__________________________________________________________________________
85/12.5 *See list after Table 1.
The cleavage value for Example 18 was 136.degree. C.
EXAMPLES 21 to 33
An adhesive blend was prepared from the segmented copolyester
described in Examples 1 to 11 and containing 20 percent Piccovar
L-30 resin, a polyindene petroleum resin having a softening point
of 30.degree. C. sold by Hercules Inc., 20 percent Piccolastic A-50
resin, a low molecular weight styrene homopolymer having a
softening point of 50.degree. C. and a melt viscosity of 29
centipoises at 190.degree. C. sold by Hercules Inc.; and 20 percent
Piccoumaron 410 HL resin described in Examples 1 to 11.
The adhesive blend and calcium oxide or other alkaline earth oxide
compound and the other components indicated in Table 3 were added
to the resin kettle and tested in the thermosel as described above
with the viscosity being determined at 190.degree. C. for the
indicated hours.
TABLE 3
__________________________________________________________________________
Stabilizer (%)* CaO/Other components Example or other oxides
Viscosity (1000 cps.) at 190.degree. C./Hours at 190.degree. C.
__________________________________________________________________________
21 1.0 29.5 Initial; 30/4; 32/8; 34/12; 36/16 CaO 22 1.0/0.25/1.0
40/Initial; 44/4; 46/8; 50/12; 53/16 CaO/PCD/1178 23 1.0/0.25/1.0
28/Initial; 31.5/4; 33/8; 32/12; 32/16 CaO/PCD/DSTDP 24
1.0/0.25/1.0 46/Initial; 48/4; 50/8; 48/12; 46/16 CaO/PCD/445 25
1.0/0.25/1.0 50/Initial; 56/4; 60/8; 60/12; 60/16 CaO/PCD/1010 26
1.5/0.25/1.0/0.5** 81/Initial; 90/6; 98/12 CaO/PCD/1010/DSTDP 27
0.25 36/Initial; 44/4; 58/8; 70/12; 72/16 BaO 28 0.40 95/Initial;
105/12 BaO 29 0.25 27.5/Initial; 30.5/2; 35/10; 32/14 MgO 30 0.40
47/Initial; 42/12 MgO 31 0.10 47/Initial; 47/7; 45/16 CaO 32
1.0/0.1 36/Initial; 60/4; 85/8; 85/12 CaO/DSTDP 33 1.0/0.1
36/Initial; 60/4; 85/8; 85/12 CaO/1178 Control None 35/Initial;
28/3; 20.5/7; 17.5/12; 13/19
__________________________________________________________________________
*See list after Table 1. 1178 - Mark 1178, Trinonylphenyl phosphite
sold by Argus Chemical Co., Brooklyn, New York. BaO - Barium Oxide,
Reagent Grade sold by General Chemical Division, Allied Chemical
Co., Morristown, New Jersey. MgO - Magnesium Oxide, Reagent Grade
sold by Fisher Chemical Co., Fair Lawn, New Jersey. **Added in form
of 50% stabilizer concentrate in 50% Elvax 250 resin, an
ethylene-vinyl-acetate resin, 28% vinyl acetate, melt index 22,
sold by E I. du Pont de Nemours and Company, Inc., Wilmington,
Delaware.
EXAMPLES 34 to 37
An adhesive blend was prepared from 40 parts of the segmented
copolyester described in Examples 1 to 11 and containing 8 parts
Piccolastic A-50 resin and 10 parts Piccovar L-30 resin described
in Examples 21 to 33; 23 parts Piccoumaron 410 HL resin and 15
parts of barium sulfate described in Examples 1 to 11; and 1 part
pyromellitic dianhydride (PMDA) sold by E. I. Du Pont de Nemours
and Co., Inc., Wilmington, Delaware.
The adhesive blend, calcium oxide and other components indicated in
Table 4 were added to the resin kettle and tested in the thermosel
as described above with the viscosity being determined at
190.degree. C. for the indicated hours.
TABLE 4
__________________________________________________________________________
Stabilizer* (parts) Example CaO/Other components Viscosity (1000
cps.) at 190.degree. C./Hours at 190.degree. C.
__________________________________________________________________________
34 2.0 121/Initial; 112/4.5; 98/12 CaO 35 2.0/0.25 100/Initial;
90/4; 85/8; 79/12; 74/16 CaO/PCD 36 2.0/1.0 114/Initial; 110/3.3;
105/6.5 CaO/1010 37 2.0/0.25/1.0/0.5 102/Initial; 94/4; 86/8;
80/12; 74/16 CaO/PCD/1010/DSTDP Control None 100/Initial; 46/4;
28.5/8; 21.5/12; 17/16
__________________________________________________________________________
*See list after Table 1.
The cleavage value for Example 35 was 122.degree. C.
EXAMPLES 38 to 40
An adhesive blend was prepared from 40 parts of the segmented
copolyester described in Examples 1 to 11 and containing 13 parts
Piccovar L-30 resin described in Examples 21 to 33; 20 parts
Piccoumaron 410 HL resin and 27 parts barium sulfate described in
Examples 1 to 11; and 1 part pyromellitic dianhydride (PMDA).
The adhesive blend, calcium oxide and other components indicated in
Table 5 were added to the resin kettle and tested in the thermosel
as described above with the viscosity being determined at
190.degree. C. for the indicated hours.
TABLE 5
__________________________________________________________________________
Stabilizer* (parts) Example CaO/Other components Viscosity (1000
cps.) at 190.degree. C./Hours at 190.degree. C.
__________________________________________________________________________
38 1.5/0.25/1.0/0.5** 260/Initial; 220/6; 205/12 CaO/PCD/1010/DSTDP
39 2.0/0.25/1.0 310/Initial; 275/6; 245/12 CaO/PCD/1010 40
2.0/0.25/1.0 175/Initial; 150/4; 136/8; 125/17 CaO/PCD/CHA 1014
Control None 145/Initial; 82/4; 55/8; 30/17
__________________________________________________________________________
*See list after Table 1. CHA 1014 - Irganox CHA 1014, nitrogen
containing hindered phenol antioxidant sold by Ciba-Geigy Co.
**Added in form of 50% stabilizer concentrate in 50% Elvax 250
resin.
The cleavage and shear values for Example 39 were 95.degree. C. and
140.degree. C., respectively.
EXAMPLES 41 to 45
An adhesive blend was prepared from 40 parts of the segmented
copolyester described in Examples 1 to 11 and containing 20 parts
Piccovar L-30 resin and 20 parts Piccolastic A-50 resin described
in Examples 21 to 33; and 20 parts Piccoumaron 410 HL resin; and 1
part pyromellitic dianhydride (PMDA).
The adhesive blend, calcium oxide and other components indicated in
Table 6 were added to the resin kettle and tested in the thermosel
as described above with the viscosity being determined at
190.degree. C. for the indicated hours.
TABLE 6
__________________________________________________________________________
Stabilizer* (parts) Example CaO/Other components Viscosity (1000
cps.) at 190.degree. C./Hours at 190.degree. C.
__________________________________________________________________________
41 1.5/0.25/1.0/0.5** 40/Initial; 38/6; 36/12/ 35/16
CaO/PCD/1010/DSTDP 42 2.0/0.25/1.0/0.25 55/Initial; 52/4; 48/8;
44/12; 42/16 CaO/PCD/1010/DSTDP 43 2.0/0.25/0.5/0.5 57/Initial;
53/4; 48/8; 41/14 CaO/PCD/1010/DSTDP 44 2.0/0.25/0.1/0.5
60/Initial; 57/4; 53/10; 50/16 CaO/PCD/1010/DSTDP 45
2.0/0.25/0.5/0.1 63/Initial; 60/8; 56/16 CaO/PCD/1010/DSTDP Control
None 35/Initial; 20/7; 13/19
__________________________________________________________________________
*See list after Table 1. **Added in form of 50% stabilizer
concentrate in 50% Elvax 250 resin.
The cleavage values, thermal and thermal-oxidative, for the
indicated examples are as follows. The thermal-oxidative
determinations were made after six hours of thermal-oxidative
exposure on a thermal roll at 190.degree. C. in air.
______________________________________ Cleavage Values (.degree.
C.) Example Thermal Thermal-Oxidative
______________________________________ 42 113 106 43 117 112 44 121
115 45 128 113 ______________________________________
EXAMPLES 46 to 48
An adhesive blend similar to the blend of Examples 1 to 11 was
prepared except that in place of the PTMEG of the copolyester there
was present 42.6 percent polyethylene glycol of molecular weight
4000. The short chain ester content was 42.7 percent, the melting
point of the copolyester was 161.degree. C. measured by thermal
mechanical analysis and the melt index was 4.6 at 190.degree.
C.
The adhesive blend, calcium oxide and other components indicated in
Table 7 were added to the resin kettle and tested in the thermosel
as described above with the viscosity being determined at
190.degree. C. for the indicated hours.
TABLE 7 ______________________________________ Stabilizer* (%)
Viscosity (1000 cps.) at Example CaO/PCD 190.degree. C./Hours at
190.degree. C. ______________________________________ 46 1.5
175/Initial; 180/4; 165/8; 140/12 CaO 47 0.25 150/Initial; 100/4;
65/8; 47/12 PCD 48 1.5/0.25 130/Initial; 130/4; 115/8; 98/12
CaO/PCD Control None 120/Initial; 80/4; 60/8; 45/12
______________________________________ *See list after Table 1.
EXAMPLES 49 to 52
An adhesive blend similar to the blend of Examples 38 to 40 was
prepared except that the copolyester described in Examples 46 to 48
was utilized.
The adhesive blend, calcium oxide and other components indicated in
Table 8 were added to the resin kettle and tested in the thermosel
as described above with the viscosity being determined at
190.degree. C. for the indicated hours.
TABLE 8 ______________________________________ Stabilizer* (%)
CaO/Other Viscosity (1000 cps.) at Example components 190.degree.
C./Hours at 190.degree. C. ______________________________________
49 2.0 175/Initial; 210/4; 210/8; 205/12 CaO 50 0.25 70/Initial;
20/4; 9.5/8; 6/12 PCD 51 2.0/0.25 185/Initial; 200/4; 220/8; 225/12
CaO/PCD 52 2.0/0.25/1.0 140/Initial; 145/4; 148/8; 148/12
CaO/PCD/1010 Control None 43/Initial; 15/4; 6.4/8; 3.9/12
______________________________________ *See list after Table 1.
EXAMPLE 53
An adhesive blend similar to the blend of Examples 41 to 45 was
prepared except that the segmented copolyester was derived from
about 31.3 percent terephthalic acid; 17.4 percent
1,4-cyclohexanedicarboxylic acid, 30.5 percent butanediol and 20.8
percent PTMEG having a molecular weight of about 1000 containing
about 76.8 percent short chain ester units and having a melting
point of 139.degree. C. measured by differential thermal analysis,
a melt index of about 7 measured at 190.degree. C., an inherent
viscosity of about 1.1 and an acid number of 1.2.
The adhesive blend, calcium oxide and polycarbodiimide indicated in
Table 9 were added to the resin kettle and tested in the thermosel
as described above with the viscosity being determined at
190.degree. C. for the indicated hours.
Table 9 ______________________________________ Stabilizer* (%)
Viscosity (1000 cps.) at Example CaO/PCD 190.degree. C./Hours at
190.degree. C. ______________________________________ 53 2.0/0.25
30/Initial; 25.5/4; 23/8; 21/12; 19.5/16 CaO/PCD Control None
32/Initial; 28/4; 16/8; 11.5/12; 8.4/16
______________________________________ *See list after Table 1.
EXAMPLE 54
An adhesive blend was prepared similar to the blend of Examples 21
to 33 except that the segmented copolyester used is described in
Example 53.
The adhesive blend, calcium oxide and polycarbodiimide indicated in
Table 10 were added to the resin kettle and tested in the thermosel
as described above with the viscosity being determined at
190.degree. C. for the indicated hours.
Table 10 ______________________________________ Stabilizer* (%)
Viscosity (1000 cps.) at Example CaO/PCD 190.degree. C./Hours at
190.degree. C. ______________________________________ 54 1.5/0.25
38/Initial; 37/4; 36/8; 33.5/12, 31.5/16 CaO/PCD Control None
20/Initial; 17/4; 14.5/8; 13/12; 11.5/16
______________________________________ *See list after Table 1.
EXAMPLE 55
An adhesive blend was prepared similar to Examples 38 to 40 except
that the segmented copolyester used is described in Example 53.
The adhesive blend, calcium oxide and other components indicated in
Table 11 were added to the resin kettle and tested in the thermosel
as described above with the viscosity being determined at
190.degree. C. for the indicated hours.
TABLE 11
__________________________________________________________________________
Stabilizer* (%) Viscosity (1000 cps.) at Example CaO/Other
components 190.degree. C./Hours at 190.degree. C.
__________________________________________________________________________
55 1.5/0.25/1.0/0.5** 310/Initial; 280/4; 255/8; 235/12; 220/16
CaO/PCD/1010/DSTDP
__________________________________________________________________________
*See list after Table 1. **Added in form of 50% stabilizer
concentrate at 50% Elvax 250 resin.
EXAMPLE 56
An adhesive blend was prepared from 25 percent of a segmented
copolyester derived from 14.3 percent terephthalic acid, and 6.1
percent isophthalic acid, 10.7 percent butanediol and 68.0 percent
PTMEG having a molecular weight of about 2100, containing 0.5
percent Ethyl 330, hindered phenol made by Ethyl Corp., Baton
Rouge, La. and 27 percent short chain ester units and having a
melting point of 97.degree. C. measured by differential thermal
analysis, a melt index of 5-7 measured at 190.degree. C., an
inherent viscosity of 1.17, and an acid number of less than 2 and
containing 24 percent Piccolastic A-25, 16.5 percent Piccolastic
A-75, 20 percent Piccotex LC, 4.5 percent Elvax 40 and 10 percent
Paraflex G-62, 2.0 percent calcium oxide, 0.25 percent Stabaxol PCD
and 0.50 percent Irganox 1010. Piccolastic A-25 and A-75 are
similar to Piccolastic A-50 described in Examples 1 to 11 except
that the softening points of the styrene polymer are 25 and 75,
respectively. Piccotex LC is a liquid .alpha.-methyl styrene vinyl
toluene copolymer manufactured by Hercules, Inc. Elvax 40 is an
ethylene vinyl acetate resin, 40% vinyl acetate, melt index 57,
sold by E. I. Du Pont de Nemours and Company, Inc.; Paraflex G-62
is an expoxidized soybean oil plasticizer sold by Rohm and Haas Co.
Stabaxol PCD and Irganox 1010 are described in Examples 1 to 11.
The blend was tested in the thermosel as described above with the
viscosity being determined at 190.degree. C. for the indicated
hours:
18/Initial; 13/12 hours.
EXAMPLE 57
An adhesive blend was prepared using 30 percent of the segmented
copolyester described in Example 56 and containing 33 percent
Piccovar L 30, 33 percent Piccotex 75, 4.0 percent XPS-250-40, 2.0
percent calcium oxide, 0.25 percent Stabaxol PCD and 0.5 percent
Irganox 1010. Piccovar L-30 is described in Examples 1 to 11,
Piccotex 75 and XPS-250-40 are similar to Piccotex LC except that
the melting points are 75.degree. and 40.degree. C., respectively.
Stabaxol PCD and Irganox 101 are described in Examples 1 to 11. The
blend was tested in the thermosel as described above with the
viscosity being determined at 190.degree. C. for the indicated
hours:
EXAMPLE 58
The following adhesive blend formulations were prepared and tested
as described above with the viscosity being determined at
190.degree. C. for the indicated hours. The results of aging are
set forth in Table 12. The controls contain no stabilizer.
TABLE 12
__________________________________________________________________________
Percentage of Components in Formulation No. Formulation (g.) (1)
(2) (3) (4) (5) (6) (7) (8) (9) (10) Control
__________________________________________________________________________
Copolyester Examples 1 to 11-CaO 1.0 g./PCD 0.25 g. 41.25 41.25
41.25 41.25 41.25 100 (a) (b) (c) (d) 100 (e) Piccovar L-30 Resin
20 -- -- 10 20 -- -- -- -- -- -- Piccolastic A-50 Resin 20 -- -- 8
20 -- -- -- -- -- -- Piccoumaron 410 HL Resin 20 7 -- 23.5 20 -- --
-- -- -- -- Nevillac X-66 Resin -- 13 13 -- -- -- -- -- -- -- --
Nevillac Super Hard Resin -- 13 13 -- -- -- -- -- -- -- -- Atlac
382E -- -- 7 -- -- -- -- -- -- -- -- Barium Sulfate -- 27 27 15 --
-- -- -- -- -- -- Pyromellitic Dianhydride (PMDA) -- -- -- 1 1 --
-- -- -- -- --
__________________________________________________________________________
(a) 0.25% PCD in copolyester. (b) 1.0% CaO in copolyester. (c)
1.0/0.25 in Copolyester CaO/PCD (d) 0.5/0.25 in copolyester CaO/PCD
(e) unstabilized copolyester
Thermosel Viscosity (1000 cps.) at 190.degree. C./Hours at
190.degree. C. Formulation No. Initial 4 8 12 16
__________________________________________________________________________
1 58 58 58 56 54 Control 35 27 21.5 17.5 14.5 2 225 230 225 210 200
Control 167 120 85 62 47 3 410 460 420 410 410 Control 260 175 120
85 -- 4 190 170 150 140 -- Control 100 46 29 21.5 -- 5 50 44 40
37.5 35 Control 35 8.5 -- -- -- 6 * 215 182 150 130 -- Control *
142 73 46 33 -- 7 (a) 1,950 1,850 1,700 1,550 1,420 8 (b) 1,950
1,830 1,800 1,750 1,700 9 (c) 2,000 2,000 2,000 2,000 2,000 10 (d)
2,000 2,000 1,980 1,880 1,800 Control 1,400 880 640 500 --
__________________________________________________________________________
* 200.degree. C. All controls contain no added stabilizer
* * * * *